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1.
The dispersion of the depolarization ratio of two prominent Raman lines (1,375 cm–1 and 1,638 cm–1) of oxyhemoglobin-N-ethyl succinimide have been examined for pH values between pH=6.0 and 8.5. Both exhibit a significant pH dependence. Calculation of the Raman tensor in terms of a fifth-order time dependent theory provides information about the pH-dependence of parameters reflecting symmetry classified distortions of the prosthetic heme group. To correlate these distortions with the functional properties of the molecule the following protocol was used: 1) An allosteric model suggested by Herzfeld and Stanley (1974) has been applied to O2-binding curves measured at different pH values between 6.5 and 9.0. From this calculation one obtains both, the energy differences between different molecular conformations and the equilibrium constants of oxygen and proton binding. 2) A titration model was formulated relating each conformation of a molecule to a distinct set of distortion parameters of the heme group. 3) The distortion parameters resulting from the analysis of our Raman data were assigned as an effective value due to incoherent superposition of the distortion parameters related to the different titration states. The application of this procedure yields an excellent reproduction of the pH-dependent effective distortion parameters of both Raman lines investigated. It is shown that the protonation of two tertiary effector groups located in the -subunits affect the symmetry of the heme in a contrary manner: the protonation of a His-residue (pK=8.2, probably His(FG4)) causes a symmetric position of the proximal imidazole thus lowering the perturbations of the heme core. Further it influences the interaction between amino acid residues of the heme cavity and pyrrole side chains (probably Val (FG5)-vinyl (pyrrole 3) thus causing a decrease of the distortions related to the peripheral part of the heme. In contrast, the protonation of Lys (EF6) causes a tilt position of the proximal imidazole and an increase of asymmetric perturbations of the heme core, whereas the interaction between the pyrrole side chains and the heme cavity is weakened. Our results are consistent with stereochemical predictions of Moffat (1971) concerning the existence of an H-bond between His(FG4) and Cys(F9).Abbreviations DPR
depolarization ratio
- EP
excitation profile
- HbA
human hemoglobin
- oxyHb
oxyhemoglobin
- NEM
N-ethyl-maleimide
- NES
N-ethyl-succimide
- BME
Bis (N-maleimidodimethyl)ether 相似文献
2.
Jørn Ditzel Else Hove 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1965,50(3):221-224
Summary The normal distribution of the serum proteins, as determined by paper-electrophoresis in eighty-seven Syrian hamsters, is reported.The effect of different corticosteroids (cortisone acetate and prednisone) on the serum proteins of the hamster has also been evaluated. Cortisone acetate produced a decrease in the
1-
2- and -globulins, while prednisone produced a decrease in the - and -globulins, an increase in albumin and a marked hyperlipemia.
Zusammenfassung Die normale Verteilung der Serumproteine wurde mit Papierelektrophorese in 87 Goldhamstern bestimmt.Die Wirkung verschiedener Corticosteroide (Cortisonazetat und Prednison) auf die Serumproteine des Hamsters wurde bestimmt. Cortisonazetat rief eine Abnahme der 1- 2- und -Globuline hervor, während Prednison eine Abnahme der - und -Globuline, eine Zunahme des Albumins und eine bedeutende Hyperlipämie hervorrief.相似文献
3.
Johannes Müthing Frank Unland Dagmar Heitmann Michaela Orlich Franz-Georg Hanisch Jasna Peter-Katalinić Vera Knäuper Harald Tschesche Sørge Kelm Roland Schauer Jürgen Lehmann 《Glycoconjugate journal》1993,10(1):120-126
The structures of gangliosides from human granulocytes were elucidated by fast atom bombardment mass spectrometry and by gas chromatography/mass spectrometry as their partially methylated alditol acetates. In human granulocytes besides GM3 (II3Neu5Ac-LacCer), neolacto-series gangliosides (IV3Neu5Ac-nLcOse4Cer, IV6Neu5Ac-nLcOse4Cer and VI3Neu5Ac-nLcOse6Cer) containing C24:1, and to some extent C22:0; and C16:0 fatty acid in their respective ceramide portions, were identified as major components. In this study we demonstrate that gangliosides from human granulocytes, the second most abundant cells in peripheral blood, can serve as receptors for influenza viruses A/PR/8/34 (H1N1), A/X-31 (H3N2), and a parainfluenza virus Sendai virus (HNF1, Z-strain). Viruses were found to exhibit specific adhesion to terminal Neu5Ac2-3Gal and/or Neu5Ac2-6Gal sequences as well as depending on the chain length of ganglioside carbohydrate backbones from human granulocytes, these important effector cells which represent the first line of defence in immunologically mediated reactions.
Abbreviations: FAB-MS, fast atom bombardment mass spectrometry; GC/EIMS, gas chromatography/electron impact mass spectrometry; GSL(s) glycosphingolipids; HPTLC, high performance thin-layer chromatography; Neu5Ac,N-acetylneuraminic acid [26], PFU, plaque forming unit. The designation of the following glycosphingolipids follows the IUPAC-IUB recommendations, and the ganglioside nomenclature system of Svennerholm was used. LacCer or lactosylceramide, Gal1-4Glc1-1Cer gangliotetraosylceramide or GgOse4Cer, Gal1-3GalNAc1-4Gal1-4Glc1-1Cer; lacto-N-tetraosylceramide or nLcOse4Cer, Gal1-4GlcNAc1-3Gal1-4-Glc1-1Cer; lacto-N-norhexaosylceramide or nLcOse6Cer, Gal1-4GlcNAc1-3Gal1-4GlcNAc1-3Gal 1-4-Glc1-1Cer; GM3, II3Neu5Ac-LacCer; GM1, II3Neu5Ac-GgOse4Cer; GD1a, IV3Neu5Ac, II3Neu5Ac-GgOse4Cer; GD1b, II3(Neu5Ac)2-GgOse4Cer; GT1b, IV3Neu5Ac, II3(Neu5Ac)2-GgOse4Cer; GQ1b, IV3(Neu5Ac)2, II3(Neu5Ac)2-GgOse4Cer; sialyllacto-N-tetraosylceramide, IV3Neu5Ac/IV6Neu5Ac-nLcOse4Cer; sialyllacto-N-norhexaosylceramide or i-active ganglioside, VI3Neu5Ac-nLcOse6Cer. 相似文献
4.
Summary In spite of the generally well-coordinated synthesis of RNA polymerase core enzyme subunits (, and ) in Escherichia coli, a situation was found during the growth transition from exponential to stationary phase in which this coordination was broken (the order of differential repression being ; Kawakami et al. (1979)). The present study indicates that, during a certain period of the growth transition, twice as much subunit is synthesized as subunit and the overproduced subunit accumulates as the assembly intermediate 2 complex, which is rapidly and preferentially degraded.Two independent factors, i.e., carbon source down-shift and oxygen depletion, were examined separately for their influence on the coordinated regulation of the synthesis of RNA polymerase subunits. The depletion of glucose added as a sole carbon source was accompanied by repression of the synthesis of all core enzyme subunits, while under the same conditions the differential rate of subunit synthesis increased. In contrast, the sudden ending of the oxygen supply resulted in specific repression of the synthesis of only and subunits but not of and subunits. The latter result may be explained by the autogenous repression of the rpoBC genes by a temporal increase in the amount of unused cytoplasmic RNA polymerase.Paper XI in this series is Kawakami and Ishihama (1980) 相似文献
5.
Biochemical documentation of allelic variation of the I-E antigens of the d,k, p,r, and u haplotypes 总被引:1,自引:0,他引:1
John M. Kupinski Pamela A. Gamble Chella S. David Dr. John H. Freed 《Immunogenetics》1982,16(5):393-405
The extent of allelic variation of the E and E
polypeptide chains of the I-E antigens from the H-2>
d
,H-2
k
, H-2
p
, H-2
r
, and H-2
u
haplotypes is described. E and E
chains were individually labeled with arginine or lysine and compared by tryptic peptide analysis. The results indicate minimum variability among the E polypeptides encoded by the d, k, p, and r haplotypes. However, the E
u
chain differed significantly from the other allelic E gene products. On the other hand, the E
alleles demonstrated substantial variability with the E
d
being notably less similar to the other alleles than they are to each other. These findings are consistent with a number of observations regarding the serology and functions of the I-E antigens.Abbreviations MHC
major histocompatibility complex
- NMS
normal mouse serum
- NP-40
Nonidet P-40
- NTS
0.25% NP-40, 10 mM Tris-Cl, 0.15 M NaCl (pH 7.4)
- SDS
sodium dodecylsulfate
- SDS-PAGE
polyacrylamide gel electrophoresis in the presence of SDS 相似文献
6.
D. F. Stiffler S. Eskandari 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1994,164(5):355-361
Larval and adult Ambystoma tigrinum were subjected to acidosis by infusing lactic acid (2 M·g-1) into the peritoneal cavity. Blood was sampled at intervals to establish the time-course of the ensuing acidosis. Both larvae and adults became significantly acidotic after 1 h. The larval acidosis was more pronounced (-4 pH units versus-2 pH units) than adults due to greater extracellular buffering capacity (higher [HCO3
-]) in adults. Both forms recovered in about 8 h. Larvae showed a typical increase in circulating norepinephrine during the initial stages of the acidosis; adults did not, having significantly lower norepinephrine titer than larvae during the acidosis. Both larvae and adults showed transient increases in PO2 during the acidosis. The 1 and 2 antagonists, timolol and butoxamine respectively, (0.2 g·g-1) were administered to separate groups of larvae. Butoxamine (2) delayed the recovery from the acidosis by prolonging the increase in arterial PCO2 and reversing the recovery of [HCO3
-]. Timolol (1) did not delay recovery. We conclude that 2 receptors are involved in the catecholamine responses to acidosis in larvae. Catecholamines appear not to play the same role in adult acid-base disturbances as they seem to in larvae.Abbreviations RBC
red blood cell 相似文献
7.
Johannes Müthing Jasna Peter-Katalinić Franz-Georg Hanisch Frank Unland Jürgen Lehmann 《Glycoconjugate journal》1994,11(2):153-162
The aim of the present study was to investigate the ganglioside expression of the highly metastatic murine lymphoreticular tumour cell line MDAY-D2. Cells were propagated under controlled pH conditions and oxygen supply in bioreactors of 1 and 7.5l volumes by repeated batch fermentation. Gangliosides were isolated from 2.7×1011 cells, purified by silica gel chromatography and separated into mono- and disialoganglioside fractions by preparative DEAE anion exchange high performance liquid chromatography. Individual gangliosides were obtained by preparative thin layer chromatography. Their structural features were established by immunostaining, fast atom bombardment and gas chromatography mass spectrometry. In addition to gangliosides of the GM1a-pathway (GM2, GM1a and GD1a) and GM1b (IV3Neu5Ac-GgOse4Cer) and GalNAc-GM1b of the GM1b-pathway, the dis8aloganglioside GD1 (IV3Neu5Ac, III6Neu5Ac-GgOse4Cer) was found in equal amounts compared to GD1a (IV3Neu5Ac, II3Neu5Ac-GgOse4Cer). All gangliosides were substituted with C24:0,24:1 and C16:0 fatty acids, sphingosine andN-acetylneuraminic acid as the sole sialic acid.
Abbreviations: FAB-MS, fast atom bombardment-mass spectrometry; GC-MS, gas chromatography-mass spectrometry; GSL(s), glycosphingolipid(s); HPLC, high performance liquid chromatography; HPTLC, high performance thin layer chromatography; Neu5Ac,N-acetylneuraminic acid; Neu5Gc,N-glycoloylneuraminic acid [57]. The designation of the following glycosphingolipids follows the IUPAC-IUB recommendations [58] and the nomenclature of Svennerholm [59]. Gangliotriaosylceramide or GgOse3Cer, GalNAc1-4Gal1-4Glc1-1Cer; gangliotetraosylceramide or GgOse4Cer, Gal1-3GalNAc1-4Gal1-4Glc1-1Cer gangliopentaosylceramide or GgOse5Cer, GalNAc1-4Gal1-3GalNAc1-4Gal1-4Glc1-1Cer; GM2, II3Neu5Ac-GgOse3Cer; GM1a, II3Neu5Ac-GgOse4Cer; GM1b, IV3Neu5Ac-GgOse4Cer; GalNAc-GM1b, IV3Neu5Ac-GgOse5Cer; GD1a, IV3Neu5Ac, II3Neu5Ac-GgOse4Cer; GD1b, II3(Neu5Ac)2-GgOse4Cer; GD1 or GD1e, IV3Neu5Ac, III6Neu5AcGgOse4Cer; GD1e, IV3(Neu5Ac)2-GgOse4Cer; GT1b, IV3Neu5Ac, II3(Neu5Ac)2-GgOse4Cer. 相似文献
8.
Microbial transformation of ginsenoside Rb1 by Rhizopus stolonifer and Curvularia lunata 总被引:2,自引:0,他引:2
Of 49 microbial strains screened for their capabilities to transform ginsenoside Rb1, Rhizopus stolonifer and Curvularia lunata produced four key metabolites: 3-O-[-d-glucopyranosyl-(1,2)--d-glucopyranosyl]- 20-O-[-d-glucopyranosyl]-3,12, 20(S)-trihydroxydammar-24-ene (1), 3-O-[-d-glucopyranosyl-(1,2)--d- glucopyranosyl]-20-O-[-d-glucopyranosyl]-3,12, 20(S)-trihydroxydammar-24-ol (2), 3-O-[-d-gluco- pyranosyl-(1,2)--d-glucopyranosyl]-3, 12, 20(S)-trihydroxydammar-24-ene (3), and 3-O--d-glucopyranosyl-3, 12, 20(S)-trihydroxydammar-24-ene (4), identified by TOF-MS, 1H- and 13C-NMR spectral data. Metabolites 1, 3 and 4 were from the incubation with R. stolonifer, and 1 and 2 from the incubation with C. lunata. Compound 2 was identified as a new compound. 相似文献
9.
Melita Čačić Johannes Müthing Ivan Kračun Ulrich Neumann Sabine Weber-Schürholz 《Glycoconjugate journal》1994,11(5):477-485
The expression of neutral glycosphingolipids and gangliosides has been studied in human skeletal and heart muscle using indirect immunofluorescence microscopy. Transversal and longitudinal cryosections were immunostained with specific monoclonal and polyclonal antibodies against the neutral glycosphingolipids lactosylceramide, globoside, Forssman glycosphingolipid, gangliotetraosylceramide, lacto-N-neotetraosylceramide and against the gangliosides GM3(Neu5Ac) and GM1(Neu5Ac). To confirm the lipid nature of positive staining, control sections were treated with methanol and chloroform:methanol (1:1) before immunostaining. These controls were found to be either negative or strongly reduced in fluorescence intensity, suggesting that lipid bound oligosaccharides were detected. In human skeletal muscle, lactosylceramide was found to be the main neutral glycosphinogolipid. Globoside was moderately expressed, lacto-N-neotetraosylceramide and gangliotetraosylceramide were minimally expressed and Forssman glycosphingolipid was not detected in human skeletal muscle. The intensities of the immunohistological stains of GM3 and GM1 correlated to the fact that GM3 is the major ganglioside in skeletal muscle whereas GM1 is expressed only weakly. In human heart muscle globoside was the major neutral glycosphingolipid. Lactosylceramide and lacto-N-neotetraosylceramide were moderately expressed, gangliotetraosylceramide was weakly expressed and the Forssman glycosphingolipid was not expressed at all in cardiac muscle. GM3 and GM1 were detected with almost identical intensity. All glycosphingolipids were present in plasma membranes as well as at the intracellular level.
Abbreviations used: BSA, bovine serum albumin; DAPI, 4,6-diamidine-2-phenylindole-dihydrochloride; DTAF, fluorescein isothiocyanate derivative; GSL(s), glycosphingolipid(s); Neu5Ac,N-acetylneuraminic acid [50]; PBS, phosphate buffered saline. The designation of the following glycosphingolipids follows the IUPAC-IUB recommendations [51] and the nomenclature of Svennerholm [52]. Lactosylceramide or LacCer, Gal1-4Glc1-1Cer; gangliotriaosylceramide or GgOse3Cer, GalNAc1-4Gal1-4Glc1-1Cer; globotriaosylceramide or GbOse3Cer, Gall-4Gall-4Glcl-1Cer; gangliotetraosylceramide or GgOse4Cer, Gal1-3GalNAc1-4Gal1-4Glc1-1Cer; globotetraosylceramide or GbOse4Cer, GalNAc1-3Gal1-4Gal1-4Glc1-1Cer; lacto-N-neotetraosylceramide or nLcOse4Cer, Gal1-4GlcNAc1-3Gal1-4Glc1-1Cer; Forssman GSL or GbOse3Cer, GalNAc1-3GalNAc1-3Gal1-4Gal1-4Gle1-1Cer; GM3, II3Neu5Ac-LacCer; GM2, II3Neu5Ac-GgOse3Cer; GM1, II3Neu5Ac-GgOse4Cer; GD3 II3(Neu5Ac)2-LacCer; GD2, II3(Neu5Ac)2-GgOse3Cer; GD1a, IV3Neu5Ac, II3Neu5Ac-GgOse4Cer; GD1b, II3(Neu5Ac)2-GgOse4Cer. 相似文献
10.
J. T. Keltjens J. M. H. Hermans G. J. F. A. Rijsdijk C. Van der Drift G. D. Vogels 《Antonie van Leeuwenhoek》1988,54(3):207-220
F430 is the prosthetic group of the methylcoenzyme M reductase of methanogenic bacteria. The compound isolated from Methanosarcina barkeri appears to be identical to the one obtained from the only distinctly related Methanobacterium thermoautotrophicum. F430 is thermolabile and in the presence of acetonitrile or C10
in4
sup-
two epimerization products are obtained upon heating; in the absence of these compounds F430 is oxidized to 12, 13-didehydro-F430. The latter is stereoselectively reduced under H2 atmosphere to F430 by cell-free extracts of M. barkeri or M. thermoautotrophicum. H2 may be replaced by the reduced methanogenic electron carrier coenzyme F420.Abbreviations CH3S-CoM
methylcoenzyme M, 2-methylthioethanesulfonic acid
- HS-CoM
coenzyme M, 2-mercaptoethanesulfonic acid
- F430
Ni(II) tetrahydro-(12, 13)-corphin with a uroporphinoid (III) ligand skeleton
- 13-epi-F430 and 12,13-di-epi-F430
the 12, 13- and 12, 13-derivatives of F430
- 12, 13-didehydro-F430
F430 oxidized at C-12 and C-13
- coenzyme F420
7,8-didemethyl-8-hydroxy-5-deazaflavin derivative
- coenzyme F420H2
reduced coenzyme F420
- MV+
methylviologen semiquinone
- HPLC
high-performance liquid chromatography 相似文献
11.
V. Bravo F. Camacho S. Sánchez E. Castro Jaén 《Bioprocess and biosystems engineering》1993,9(4):159-165
We have studied the ethanolic fermentation of D-xylose with Pachysolen tannophilus in batch cultures. We propose a model to predict variations in D-xylose consumed, and biomass and ethanol produced, in which we include parameters for the specific growth rate, for the consumption of D-xylose and production of ethanol either related or not to growth.The ideal initial pH for ethanol production turned out to be 4.5. At this pH value the net specific growth rate was 0.26 h–1, biomass yield was 0.16 g.g–1, the cell-maintenance coefficient was 0.073 g.g–1.h–1, the parameter for ethanol production non-related to growth was 0.064 g.g–1,h–1 and the maximum ethanol yield was 0.32 g.g–1.List of Symbols
A
c
Carbon atomic weight
-
a
d1/h
Specific cell-maintenance rate defined in Eq. (8)
-
c
Mass fraction of carbon in the biomass
-
E g/l
Ethanol concentration
-
f
x
Correction factor defined in Eq. (13)
-
f
x
Correction factor defined in Eq. (13)
-
f
xi
Correction factor defined in Eq. (14)
-
k
d1/h
Death constant
-
M
E
Ethanol molecular weight
-
M
s
Xylose molecular weight
-
M
xi
Xylitol molecular weight
-
m g xylose/g biomass
Maintenance coefficient for substrate
-
m
dg xylose/g biomass
Maintenance coefficient when k
d
-
q
Eg ethanol/g biomass.
Specific ethanol production rate
-
s g/l
Residual xylose concentration
-
s
0 g/l
Initial xylose concentration
-
t h
Time
-
x g/l
Biomass concentration
-
x
0 g/l
Initial biomass concentration
-
Y
E/sg ethanol/g xylose
Instantaneous ethanol yield
-
¯Y
E/sg ethanol/g xylose
Mean ethanol yield
-
Y
E
s/T
g ethanol/g xylose
Theoretical ethanol yield
-
Y
E
s/*
g ethanol/g xylose
Corrected instantaneous ethanol yield
-
¯Y
E
s/*
g ethanol/g xylose
Corrected mean ethanol yield
-
Y
x/sg biomass/g xylose
Biomass yield
-
¯Y
xi/sg xylitol/g xylose
Mean xylitol yield
Greek Letters
g ethanol/g biomass
Growth-associated product formation parameter
-
g ethanol/g biomass.h
Non-growth-associated product formation parameter
-
dg ethanol/g biomass.h
Non-growth-associated product formation parameter when k
d0
-
h
Variable defined in Eq. (6) or Eq. (7)
-
1/h
Specific growth rate
-
m1/h
Maximum specific growth rate 相似文献
12.
The transient state analysis of the consecutive sequence of reactions S P
1 P
2 taking place inside a porous spherical coimmobilized biocatalyst is discussed for the case in which each step follows Michaelis Menten type kinetics. The theoretical analysis includes intraparticle diffusional limitations. The model equations are solved by the explicit finite difference method. The effect of various parameters of importance on the batch reactor performance is discussed. Comparison of the model with experimental results has been shown.List of Symbols
c
p
Dimensionless substrate concentration inside the particle, (s
p/ss
o)
-
c
pi, j
Dimensionless substrate concentration inside the particle at i, j
-
c
s
Dimensionless substrate concentration at the surface of the particle, (s
s/s
0)
-
d
p cm
particle diameter
-
D
s, D
p cm2/s
Diffusion coefficient of the substrate S and intermediate P
1 inside the particle respectively
-
h
Space step size inside the particle
-
i
Grid point inside the particle
-
j
Grid point along the time coordinate
-
k
Time step size
-
K
m1, K
m2 g/l
Michaelis constants for the first and second reaction respectively
-
K
I1,K
I2 g/l
Substrate inhibition parameters for first and second reaction respectively
-
P
m g/l
Product inhibition parameter for the second reaction
-
P
1p
, P
1s
g/l
Concentration of the intermediate inside the particle and at the surface of the particle respectively
-
P
2p
, P
2s
g/l
Concentration of the product P
2 inside the particle and at the surface of the particle respectively
-
p
1p
Dimensionless intermediate concentration inside the particle, (p
1p/s0)
-
p
1s
Dimensionless intermediate concentration at the surface of the particle, (p
1s
/S
0)
-
P
2p
Dimensionless product concentration inside the particle, (p
2p
/S0)
-
p
2s
Dimensionless product concentration at the surface of the particle, (p
2s/S0)
-
p
1pi, j
Dimensionless intermediate concentration inside the particle at i, j
-
P
2pi, j
Dimensionless product concentration inside the particle at i, j
-
q
Ratio of diffusion coefficients, D
p/D
s
-
r cm
Radial position inside the particle
-
R cm
Radius of the pellet
-
S
0 g/l
Initial substrate concentration in the bulk liquid
-
S
p g/l
Substrate concentration inside the particle
-
S
s g/l
Substrate concentration at the surface of the particle
-
t s
Time,
-
V
max1 g/(ls)
Maximum reaction velocity for the first reaction
-
V
max2 g/(ls)
Maximum reaction velocity for the second reaction
-
y
Dimensionless radial distance, (r/R)
-
y
1, j
Dimensionless radial distance at i, j
Greek Letters 1
Parameter, S
0/K
m1
- 2
Parameter, S
0/K
m2
-
I1
Parameter, S
0/K
I1
-
I2
Parameter, S
0/K
I2
-
I3
Parameter, S
0/P
m
-
Dimensionless time defined as (D
s
t/R
2)
-
1
2
V
max1R 2/Km1Ds
-
2
2
V
max2R 2/Km2Ds 相似文献
13.
n-Octyl -d-xylotrioside, xylobioside and xyloside, which are effective next-generation surfactants, can be prepared by the one-step reaction of xylan and n-octanol using the acetone powder (acetone-dried cells) of Aureobasidium pullulansas the enzyme source of xylanase in supercritical carbon dioxide (CO2) and fluoroform (CHF3) fluids. Yields of the n-octyl glycosides were significantly increased using supercritical CHF3, and the total yields of the n-octyl -d-glycosides exceeded 250 mg g–1 xylan. n-Octyl -d-xylotrioside was produced only by using supercritical fluids. 相似文献
14.
John D. Abernethy 《Biological cybernetics》1974,14(4):187-200
The theoretical properties of synapses such as those in the retina which operate on graded potentials are developed using work on tetrodotoxin-treated synapses as a basis. A linearized model of a two-synapse negative feedback loop analogous to the bipolaramacrine feedback loop in the retina possesses a frequency response which developes an increasingly prominent resonance peak at higher input levels and under some circumstances shows instability. Psychophysical studies have shown that the visual system also exhibits this behaviour suggestive of progressive underdamping in a harmonic oscillator. Evidence in favor of the hypothesis that resonance originates in the loop is presented, the conclusions being that the loop functions to tune the retina to a range of temporal frequencies.Symbol Table
V
millivolts depolarisation relative to resting membrane potential
-
V
n
, V
out
pre-synaptic, post-synaptic depolarisation respectively
-
V
e
, V
i
reversal potential or e.m.f. of post-synaptic battery of excitatory, inhibitory synapses respectively
-
V
out
(max)
maximal post-synaptic depolarisation defined by Eq.(10c)
-
V
0
input depolarisation for feedback loop
-
depolarisation potential normalised with respect to V
out(max)
-
I
milliamperes of depolarising current
-
I
s
post-synaptic membrane current
-
I
c
cable current
-
I
0
input depolarising current for feedback loop
-
I
max
maximal physiological value for I
0
=V
e
·G
0
-
i
depolarising current normalised with respect to Imax
-
e
reversal potential normalised with respect to V
e
-
r
i
specific resistivity of internal medium
-
R
m
membrane resistance
-
C
m
membrane capacitance
-
cable space constant = R
m
/2R
i
-
g
0
characteristic cable conductance = 2/R
m
·R
i
-
G
conductance of post-synaptic membrane
-
G
s
maximal post-synaptic membrane conductance
-
g
fraction of receptors occupied by transmitter = G/G
s
-
r
the ratio G
s/G
0
-
membrane time constant = R
m·Cm
-
1
time constant of transmitter release in response to presynaptic depolarisation [Eq. (6)]
-
2
time constant of decay of g [Eq. (7a)]
-
2
2·[1+k·exp(b·v
in)]–1
-
k
equilibrium constant for transmitter-receptor interaction [Eq. (7a)]
-
b
constant determining increase in rate of transmitter release with pre-synaptic depolarisation [Eq. (6)]
-
c
concentration of transmitter in synaptic cleft normalised with respect to resting concentration
-
H
jk
(s)
linearised transfer function for synaptic transmission from neurone j to neurone k
-
G(s)
H12(s)
-
H(s)
-H21(s)
-
F(s)
linearised closed-loop transfer function
-
x
2 times spatial frequency of counterphase grating pattern
-
the ratio (1+s)/(x)2
-
a
the product (1+r)·k
-
d
density of bipolars per unit area 相似文献
15.
Keiko Tadano-Aritomi Harumi Kubo Philip Ireland Takeshi Kasama Shizuo Handa Ineo Ishizuka 《Glycoconjugate journal》1996,13(2):285-293
A novel mono-sulfated glycosphingolipid based on the gangliotriaose core structure was isolated from rat kidney. The isolation procedure involved extraction of lipids with chloroform/methanol, mild alkaline methanolysis, column chromatographies with anion exchangers and silica beads. The structure was characterized by compositional analysis, FTIR spectroscopy, methylation analysis,1H-NMR spectroscopy and negative-ion liquid secondary ion mass spectrometry (LSIMS) using the intact glycolipid and its desulfation product. The two dimensional chemical shift correlated spectroscopy provided information on the sugar sequence as well as anomeric configurations, and indicated the presence of a 3-O-sulfatedN-acetylgalactosamine within the molecule. Negative-ion LSIMS with high- and low-energy collision-induced dissociation defined the sugar sequence and ceramide composition, confirming the presence of a sulfatedN-acetylgalactosamine at the non-reducing terminus. From these results, the complete structure was proposed to be HSO3-3GalNAc1-4Gal1-4Glc1-1Cer (Gg3Cer III3-sulfate, SM2b).
Abbreviations: Abbreviations for sulfated glycolipids [17] follow the modifications of the nomenclature system of Svennerholm for gangliosides [37], and the designation of the other glycosphingolipids follows the IUPAC-IUB recommendations [38]. Cer, ceramide; LacCer, lactosylceramide, Gal1-4Glc1-1Cer; Gg3Cer, gangliotriaosylceramide, GalNAc1-4Gal1-4Glc1-1Cer; Gg4Cer, gangliotetraosylceramide, Gal1-3GalNAc1-4Gal1-4Glc1-1Cer; iGb4Cer, isoglobotetraosylceramide, GalNAc1-3Gal1-3Gal1-4Glc1-1Cer; Gb4Cer, globotetraosylceramide, GalNAc1-3Gal1-4Gal1-4Glc1-1Cer; SM4s, galactosylceramide sulfate, GalCer I3-sulfate; SM3, lactosylceramide sulfate, LacCer II3-sulfate; SM2a, Gg3Cer II3-sulfate; SM2b, Gg3Cer III3-sulfate; SB2, Gg3Cer II3,III3-bis-sulfate; SM1a, Gg4Cer II3-sulfate; SM1b, Gg4Cer IV3-sulfate; SB1a, Gg4Cer II3,IV3-bissulfate; GLC, gas-liquid chromatography; GC-MS, gas chromatography-mass spectrometry; DQF, double quantum filtered; COSY, chemical-shift-correlated spectroscopy; LSIMS, liquid secondary ion mass spectrometry; CID, collision-induced dissociation; MS/MS, tandem mass spectrometry. 相似文献
16.
A set of Lipooligosaccharides (LOSs) has previously been characterized inM. gastri W471. The structure of the highly antigenic LOS (LOS-III) was elucidated and this molecule can unambiguously distinguishM. gastri from the opportunistic pathogenM. kansasii. In the present study, the structures of three otherM. gastri W471 LOSs were determined by one-dimensional1H-NMR spectroscopy and gas liquid chromatography. They differ by the number of Xylp units and by the structure of the distal monosaccharide. The two dimensional (2D) NMR approach was successfully applied to the LOS antigen ofM. kansasii to locate the acetyl and acyl substituents and to determine the anomeric configuration of the -d-Fucp unit.The molecular specificity of anti-LOS-III antibodies was investigated and the LOS-III epitope was defined as the distal disaccharide: 3,6-dideoxy-4-C-(1,3-dimethoxy-4,5,6,7-tetrahydroxy-heptyl)--xylohexp-(1 3)--l-Xylp.Abbreviations CI
Chemical Ionisation
- COSY
1H-1H COrrelated SpectroscopY
- COSY LR
1H-1H COrrelated SpectroscopY Long Range
- DQF-COSY
Double Quantum Filtered1H-1H COrrelated SpectroscopY
- EI
Electronic Impact
- GC
Gas Chromatography
- HMBC
Heteronuclear Multiple Bond Correlation spectroscopy
- HMQC
Heteronuclear Multiple Quantum Correlation spectroscopy
- HOHAHA
HOmonuclear HArtmann-HAhn spectroscopy
- HPLC
High Performance Liquid Chromatography
-
3JH.H
vicinal spin-spin coupling constants
- LAM
LipoArabinoMannan
- LOS
LipoOligoSaccharide
- MS
Mass Spectrometry
- FAB/MS
Fast Atom Bombardment-Mass Spectrometry
-
1H- or13C- NMR
proton or carbon Nuclear Magnetic Resonance
- PBS
Phosphate Buffered Saline
- PheG1 K-I
Major phenolic glycolipids fromM. kansasii
- RCT-1, -2, -3
relayed coherence transfer 1 step, 2 steps, 3 steps
- ROESY
Rotative frame Overhauser Effect SpectroscopY
- Sugars
Fucp: fucopyranose
- Galp
galactopyranose
- Glcp
glucopyranose
- hexp
hexopyranose
- Rhap
rhamnopyranose
- Xylp
xylopyranose
- TLC
Thin Layer Chromatography
- TMS
Tri Methyl Silyl 相似文献
17.
Summary
3J
x coupling constants and complementary nuclear Overhauser data on the intraresidue C
x
H–CH distances form an essential part of the data needed to obtain stereospecific assignments of -methylene protons in proteins. In this paper we show that information regarding the magnitude of the3J
x coupling constants can be extracted from a semi-quantitative interpretation of relative peak intensities in a 3D15N-separated1H–1H Hartmann-Hahn1H–15N multiple quantum coherence (HOHAHA-HMQC) spectrum. In addition, we demonstrate that reliable information on the intraresidue C
x
H–CH distances, free of systematic errors arising from spin diffusion, can be obtained from a 3D13C-separated1H–1H rotating frame Overhauser effect1H–13C multiple quantum coherence (ROESY-HMQC) spectrum. The applicability of these experiments to larger proteins is illustrated with respect to interleukin-1, a protein of 153 residues and 17.4 kDa molecular weight.Abbreviations 1L-1
interleukin-1
- NOE
nuclear Overhauser effect
- ROE
rotating frame Overhauser effect
- HOHAHA
homonuclear Hartmann-Hahn spectroscopy
- NOESY
nuclear Overhauser enhancement spectroscopy
- ROESY
rotating frame Overhauser spectroscopy
- HMQC
heteronuclear multiple quantum coherence spectroscopy 相似文献
18.
The growth inhibitory activities of 6 endogenous growth inhibitors isolated from light-grown dwarf peas (Pisum sativum cv. Progress No. 9) were examined in the epicotyl of dark-grown seedlings of the same cultivar in the dark in order to examine the possible contribution of these compounds to the growth inhibition brought about by red light. The activities of these natural inhibitors, including two A-2 and A-2 of as yet undetermined structure, were compared with those of synthetic growth retardants and benzyladenine. Samples were applied directly into the epicotyls via a glass capillary tube. In 24-h tests doses for a 25% inhibition (I25) were: A-2, 4.3 × 10-2: cis-xanthoxin, 1.2 × 10-1 ; A-2, 1.6 × 10-1; trans-xanthoxin, 1.2; R,S-dihydromaleimide, 3.5 × 102 and pisatin, 4.0 × 102 nmol plant-1 . In 72-h tests, I25's were: benzyladenine, 1.5; AMO-1618 (ammonium-(5-hydroxycarvacryl)-trimethylchloride piperidine carboxylate), 2.4; R,S-dihydromaleimide, 4.0 × 102 and CCC (chlorocholine chloride), 1.1 × 103 nmol plant-1. -D-Glucosyl-R-dihydromaleimide had no activity at all. Benzyladenine caused the thickening as well as elongation inhibition of the epicotyls of intact plants. The possible involvement of A-2 and in the red light growth inhibition of dwarf peas is discussed.Abbreviations AMO-1618
ammonium-(5-hydroxycarvacryl)-trimethylchloride piperidine carboxylate
- CCC
chlorocholine chloride
- G-DHMD
-D-glucosyl-R-dihydromaleimide
- I25
dose required for a 25% growth inhibition
- R
red light
author for correspondence 相似文献
19.
Sujay K. Singh Edward K. Wakeland Ivica Vučak Zoltan A. Nagy Jan Klein 《Immunogenetics》1981,14(3-4):273-281
The B10.STA62 strain carries the H-2
w27 haplotype derived from a wild mouse captured in the vicinity of Ann Arbor, Michigan. Products of two class II loci composing this haplotype, A
and A
, are serologically, biochemically (by tryptic peptide mapping), and functionally indistinguishable from products controlled by the A
b
and A
/b
genes of the B10.A(5R) strain. In contrast, the polypeptide chain controlled by the third class II locus, E
, is different from that controlled by the E
/b
gene. This E
/w27
chain lacks an antigenic determinant present on the Eb molecule and carries determinants lacking on the Eb molecule, the E
/b
and E
/w27
peptide maps differ in at least six peptides, and cytotoxic T cells specific for the E
b
chains do not react with B10.STA62 target cells. This great difference between the E
/b
and E
/w27
chains suggests that the corresponding genes have not been derived from one another by a direct mutational conversion; instead, H-2
w27 appears to be a recombinant haplotype derived by crossing-over between the A
A
duplex and the E
locus. This is the first recombinant discovered separating these class II loci. 相似文献
20.
Oxygen consumption of Astyanax fasciatus (Characidae,Pisces): a comparison of epigean and hypogean populations 总被引:2,自引:0,他引:2
Kathrin Hüppop 《Environmental Biology of Fishes》1986,17(4):299-308
Synopsis The standard and routine oxygen consumptions of Astyanax fasciatus from one surface population (Rio Teapao) and three cave populations (Chica, Micos and Pachon caves: sAnoptichthys jordani, the Micosfish and Anoptichthys antrobius) were determined individually over 24 hours by the use of a flow-through respirometer and polarographic oxygen electrodes. The phylogenetically oldest Pachon fish had a significantly lower standard metabolic rate (0.230 ± 0.036 mg O2 g-1 h-1) than the epigean Teapao fish, the hybrid Chica fish and the phylogenetically younger Micos fish (0.314 ± 0.081 mg O2g--1h-1, 0.284 ± 0.048 mg O2g-1h-1, 0.277 ± 0.063 mg O2g-1h-1). No significant differences could be determined among the latter three populations. A significant difference in routine metabolic rate existed only between the Pachon fish (0.309 ± 0.0.56 mg O2g-1h-1) and the Teapao fish (0.415 ± 0.071 mg O2g-1h-1). The Chica fish (0.356 ± 0.084 mg O2g-1h-1) and the Micos fish (0.355 ± 0.080 mg O2 g-1h-1) could not be separated from either the Teapao or the Pachon fish, but a decreasing trend from the surface population through the Chica and the Micos to the Pachon population was obvious. During a starvation period of 29 days the metabolic rate of epigean Teapao and hypogean Pachon fish decreased significantly by 32.5% and 34.8% (standard oxygen consumption rate) and 27.5% and 28.2% (routine oxygen consumption rate), respectively. Body mass loss during the starvation period was 16.3% for the Teapao fish and 9.5% for the Pachon fish. 相似文献