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1.
Bruce Cherksey Robert Durrie Peter E. Braun Victor S. Sapirstein 《Neurochemical research》1994,19(8):1101-1106
This study reports the analysis of K+ channel activity in bovine periaxolemmal-myelin and white matter-derived clathrin-coated vesicles. Channel activity was evaluated by the fusion of membrane vesicles with phospholipid bilayers formed across a patch-clamp pipette. In periaxolemmal myelin spontaneous K+ channels were observed with amplitudes of 25–30, 45–55, and 80–100 pS, all of which exhibited mean open-times of 1–2 msec. The open state probability of the 50 pS channel in periaxolemmal-myelin was increased by 6-methyldihydro-pyran-2-one. Periaxolemmal-myelin K+ channel activity was regulated by Ca2+. Little or no change in activity was observed when Ca2+ was added to thecis side of the bilayer. Addition of 10 M total Ca2+ also resulted in little change in K+ channel activity. However, at 80 M total Ca2+ all K+ channel activity was suppressed along with the activation of a 100 pS Cl– channel. The K+ channel activity in periaxolemmal myelin was also regulated through a G-protein. Addition of GTPS to thetrans side of the bilayer resulted in a restriction of activity to the 45–50 pS channel which was present at all holding potentials. Endocytic coated vesicles, form in part through G-protein mediated events; white matter coated vesicles were analyzed for G proteins and for K+ channel activity. These vesicles, which previous studies had shown are derived from periaxolemmal domains, were found to be enriched in the subunits of G0, Gs, and Gi and the low molecular weight G protein,ras. As with periaxolemmal-myelin treated with GTPS, the vesicle membrane exhibited only the 50 pS channel. The channel was active at all holding potentials and had open times of 1–6 msec. Addition of GTPS to the bilayer fused with vesicle membrane appeared to suppress this channel activity at low voltages yet induced a hyperactive state at holding potentials of 45 mV or greater. The vesicle 50 pS K+ channel was also activated by the 6-methyl-dihydropyron-2-one (20 M).Abbreviations CNPase
2–3 cyclic nucleotide phosphohydrolase
- EDTA
ethylenediamine N,N,N,N-tetraacetic acid
- G-protein
GTP(guanosine triphosphate) binding protein
- GTPS
guanosine 5-O-(3-thiotriphosphate)
- MAG
myelin associated glycoprotein
- Na+
K+ ATPase, Na+ and K+ stimulated adenosine triphosphatase
- PLP
myelin proteolipid protein
Special issue dedicated to Dr. Majorie B. Lees. 相似文献
2.
Christoph Syldatk Dirk Völkel Ulrich Bilitewski Karsten Krohn Hartmut Höke Fritz Wagner 《Biotechnology letters》1992,14(2):105-110
Summary Resting cells ofArthrobacter sp. (DSM 3745) with the ability to form L-tryptophan from D,L-5-(3-indolylmethy)hydantoin were used for the bioconversion of D,L-5-- and D,L-5--naphthylmethylhydantoin (D,L-5-- and D,L-5--NMH) to the corresponding L-amino acids. Under the optimal reaction conditions of pH 9.7 and 40°C specific productivities of 0.2 (-naphtylalanine) and 0.6 (-naphtylalanine) mM amino acid x g cell dry mass–1 x h–1 were obtained in a 0.1 M Na2CO3/NaHCO3-buffer in a strirred bioreactor. 相似文献
3.
Irini Theodossiou Morten A. Olander Michael Søndergaard Owen R.T. Thomas 《Biotechnology letters》2000,22(24):1929-1933
A 20–40 m pellicular high density (3.7 g cm–3) expanded bed material has been designed for the capture of DNA and other large macromolecules. Anion exchangers fashioned out of these supports exhibited dramatically enhanced DNA binding capacities over commercial anion exchange adsorbents (6 mg ml–1, c.f. 50 g ml–1 at 10% breakthrough), due to a combination of small particle and fuzzy surface architecture created through the coupling of polyethylene imine chains. 相似文献
4.
Infrared analyses of the carrageenan in ten species (representing four genera) of Gigartinaceae and one species of Hypneaceae in different reproductive phases from the northwestern coast of Baja California were studied. Cystocarpic samples of the Gigartinaceae presented varying degrees of a / hybrid. The degree of hybridization was determined based on the ratio between the peak absorbances at 805/845 cm–1. A high correlation was observed between the 805/845 cm–1 and 805/970 cm–1 ratios. Tetrasporic samples of Gigartina leptorhynchos, Iridaea splendens, Rhodoglossum affine and R. roseum, presented a -carrageenan profile, whereas Gigartina tepida, G. exasperata, G. harveyana, G. canaliculata and G. spinosa presented a -carrageenan. The tetrasporic sample of Hypnea valentiae showed a -carrageenan with a very low degree of hybridization. 相似文献
5.
Interrelationships Between Nitrogen Supply and Photosynthetic Parameters in Vicia faba L. 总被引:2,自引:2,他引:0
We determined for Vicia faba L the influence of nitrogen uptake and accumulation on the values of photon saturated net photosynthetic rate (P
Nmax), quantum yield efficiency (), intercellular CO2 concentration (C
i), and carboxylation efficiency (C
e). As leaf nitrogen content (NL) increased, the converged onto a maximum asymptotic value of 0.0664±0.0049 mol(CO2) mol(quantum)–1. Also, as NL increased the C
i value fell to an asymptotic minimum of 115.80±1.59 mol mol–1, and C
e converged onto a maximum asymptotic value of 1.645±0.054 mol(CO2) m–2 s–1 Pa–1 and declined to zero at a NL-intercept equal to 0.596±0.096 g(N) m–2. fell to zero for an NL-intercept of 0.660±0.052 g(N) m–2. As NL increased, the value of P
Nmax converged onto a maximum asymptotic value of 33.400±2.563 mol(CO2) m–2 s–1. P
N fell to zero for an NL-intercept of 0.710±0.035 g(N) m–2. Under variable daily meteorological conditions the values for NL, specific leaf area (L), root mass fraction (Rf), P
Nmax, and remained constant for a given N supply. A monotonic decline in the steady-state value of Rf occurred with increasing N supply. L increased with increasing N supply or with increasing NL. 相似文献
6.
Gross and net nitrogen (N) ammonification and nitrification were measured in soils from an uncut and recently cut upland and peatland conifer stand in northwestern Ontario, Canada. Rates of gross total inorganic N immobilization were similar to gross mineralization, resulting in low net mineralization rates in soils from all four upland and peatland conifer stands. Gross ammonification rates were variable but similar in soils from uncut and cut peatland hollows (18–19mgNkg–1day–1) and upland forest floor soils (14–19mgNkg–1day–1). Gross ammonium (
) immobilization rates were also variable but similar to ammonification rates. Median gross nitrification rates were within 0–2mgNkg–1day–1 in soils from all four upland and peatland cut and uncut stands, although rates were consistently higher for the soils from the cut stands. Large variability in gross nitrification rates were observed in peatland soils, however the highest gross nitrification rates were measured in saturated peatland soils. Net rates remained low in the soils from all four stands due to high nitrate (
) immobilization and very fast
turnover (<0.2 day). Our results suggest that potential
losses may be negated by high immobilization in uncut and cut boreal forest stands. This study reveals the potential for the interaction of N production and consumption processes in regulating N retention in upland and peatland conifer forests, and the resilience of the boreal forest to disturbance. 相似文献
7.
Summary The short-trichome-forming, non-heterocystous and non-nitrogen-fixing (het
– nif–) mutant of the nitrogen-fixing blue-green alga Nostoc muscorum was isolated by N-methyl-N-nitro-N-nitrosoguanidine (NTG)-mutagenesis after penicillin enrichment technique and characterized. The mutant did not grow and fix nitrogen in combined-nitrogen-free medium while in nitrate-containing medium it grew well (K=0.112/day, G=64.27 h), although its growth was comparatively poor than the parent alga (K=0.128/day; G=56.14 h). The mutant was stable and both the het
– and nif
– characters reverted to wild type (het
+ nif+) with the reversion frequency of 2.62×10-7.The het
– nif– mutant tolerated 0.5 g/ml of streptomycin sulphate on the agar medium and its streptomycin resistant mutant capable of growing in presence of 10g/ml of streptomycin was isolated spontaneously with a frequency of 1.45×10-8. These streptomycin resistant isolates (het
– nif– strR) resisted 100 g/ml of streptomycin sulphate on the agar medium and 200 g/ml in liquid medium. Spontaneous virus-resistant mutant of het
– nif– strR was isolated with a mutation frequency of 4.02×10-4.The data of genetic recombination experiments suggested that there is transfer of both het and nif genes to het
– nif– strain with the frequency of 2×10-6 to 2×10-5 simultaneously. There was increase in recombination frequency with increasing the incubation period. The virus-resistance marker is also transferred to the sensitive recipient.Abbreviations CFU
colony forming units
- C–N
Chu-10 medium without combined nitrogen
- C+N
Chu-10 medium with 0.232 g/l calcium nitrate
- G
generation time
-
het
heterocyst differentiating genes
- K
specific growth rate constant
- MOI
multiplicity of infection
-
nif
nitrogen-fixing genes
- NTG
N-methyl-N-nitro-N-nitrosoguanidine
- PFU
plaque forming units
-
str
R
streptomycin resistance
-
str
R
streptomycin sensitive 相似文献
8.
Rajkhowa R.C. Goswami Pranab Singh H.D. 《World journal of microbiology & biotechnology》2000,16(1):63-68
The mechanism of uptake of water-insoluble -sitosterol by a newly isolated strain of Arthrobacter
simplex SS-7 was studied. The production of an extracellular sterol-pseudosolubilizing protein during growth of A. simplex on -sitosterol was demonstrated by isolating the factor from the cell-free supernatant and its subsequent purification by Sephadex G-150 column chromatography. The M
r of the purified sterol-pseudosolubilizing protein determined by SDS–PAGE was 19kDa. The rate of sterol pseudosolubilization (5.2×10–3g l–1h–1) could not adequately account for the rate of sterol uptake (72×10–3g l–1h–1) and the specific growth rate (56×10–3 h–1). However in the unfavourable growth condition, when the cells were treated with sodium azide at the level of 30–60% of MIC, the sterol pseudosolubilization accounted for nearly 74% of the total growth containing 96% free cells. Cellular adherence to substrate particles was found to play an active role in the normal growth of the strain on -sitosterol. Unlike sodium acetate-grown cells, whose surface activity was negligible (60mNm–1), the sterol-grown cells had strong surface activity (40mNm–1). The high lipid content and long chain fatty acids in the cell-wall of -sitosterol-grown cells probably contribute to the high sterol adherence activity of the cells. 相似文献
9.
Desana Li >sková José Ruiz Ordóñez Alexander Lux Alfredo Piñeyro López 《Plant Cell, Tissue and Organ Culture》1994,36(3):339-343
Isolated embryos ofKarwinskia humboldtiana were cultured in vitro. The growth of embryos and development to plantlets on woody plant medium supplemented with indole-3-acetic acid 6.10-2 mol l–1, gibberellic acid (GA3) 3.10-2 mol l–1, and 6-benzylaminopurine (BA) 2 mol l–1 was obtained. Multiplication of shoots and rooting of excised shoots has been achieved. Callus formation on modified Murashige-Skoog medium supplemented with 1-naphthaleneacetic acid 10 mol l–1, GA3 14 mol l–1, and kinetin 5 mol l–1 on hypocotyls, or on root cultures on medium supplemented with 2.4-dichlorophenoxyacetic acid 10 mol l–1 and BA 10 mol l–1 was induced.Abbreviations BA
6-benzylaminopurine
- 2,4-d
2,4-dichlorophenoxyacetic acid
- GA3
gibberellic acid
- IAA
indole-3-acetic acid
- NAA
1-naphthaleneacetic acid
- TEM
transmission electron microscopy 相似文献
10.
Summary The surface tension and foaminess of (a) unlimited, (b) substrate limited, and (c) oxygen transfer limited growth media of Hansenula polymorpha were measured using methanol, ethanol or glucose as a substrate.The time dependence of can be described by the Avrami-Überreiter relationship: log (2.3 log V)=n log t+log b, where V = (O – eq/(t – eq, and O, t and eq are at tM=0, tM=t and tM (equilibrium value).The constants n and b are functions of the fermentation time tF as long as the growth is unlimited but they are constant in the state of limited growth. With glucose substrate, the foaminess can be presented as a definite function of the time, tDG, which is necessary to attain eq. With alcohol as a substrate no definite (tDG) function was found.Symbols b
constant in Eq. (1)
- n
constant in Eq. (1)
- S
substrate concentration
- T
temperature
- tM
time h (measured from the beginning of the determination of the surface tension )
- tF
cultivation time h (measured from the time of inoculation)
- tDG
time (min) necessary to attain the equilibrium surface tension )
- X
dry biomass concentration (gl–1)
- V
(O – eq)/(t – eq)
- VS
equilibrium volume of the foam (cm3)
- VG
volumetric gas flow rate during the estimation of (cm3 s–1)
- vvm
volumetric gas flow rate with regard to the volume of the medium (min–1)
- wSG
superficial gas velocity (cm s–1)
- m
maximum specific growth rate (h–1)
-
VS/VG foaminess (s)
-
surface tension, mMm–1 (milli Newton m–1)
- O
at tM=0
- eq
equilibrium surface tension ( at tM)
- t
at tM=t
- HP
probes from Hansenula polymorpha cultivation
- NLG
non limited growth
- OTLG
oxygen transfer limited growth
- SLG
substrate limited growth 相似文献
11.
Alpha-thalassemia in Papua New Guinea 总被引:6,自引:0,他引:6
P. Yenchitsomanus K. M. Summers P. G. Board K. K. Bhatia G. L. Jones K. Johnston G. T. Nurse 《Human genetics》1986,74(4):432-437
Summary A study of the distribution of -thalassemia in Papua New Guinea (PNG) was carried out by DNA analysis. A total of 664 DNA samples were screened for -thalassemia 2 and -thalassemia 1 caused respectively by either deletion of one or both of the duplicated -globin genes. -Thalassemia 2 was detected in high frequencies in coastal and lowland regions where malaria has been holo- to hyperendemic but in low frequencies in non-malarious highland regions. The highest frequency was observed in the north coast of PNG. The distribution of -thalassemia 2 seems to be in accordance with other conditions such as ovalocytosis and G6PD deficiency which are also prevalent in this population, suggesting that they may interact in protection against malaria. However, it appears to be negatively correlated with -thalassemia and -thalassemia 1, the latter being extremely rare in this population. Analysis of the types and subtypes of the single -globin gene deletion revealed a predominance of the –4.2 type in general, except in some regions in the south where the –3.7 type is prevalent. The –3.7 I subtype is the common form of the –3.7 deletion in the PNG mainland. The –3.7 III subtype, previously reported to be unique in Melanesians and Polynesians, was detected in an offshore island of PNG. However, this subtype is very rare in Melanesians from the PNG mainland. 相似文献
12.
J. Sybenga 《Genetica》1965,36(1):243-252
Whilst reliable estimates of chiasma frequencies can usually not be obtained, the probability (b) of a chromosome arm to be bound by at least one chiasma can often be determined. In the absence of interference this probability equals (1–e
–2), where 2 is the average chiasma frequency of the chromosome arm and the average crossover frequency or map length. In the presence of interference is shown to retain its genetic meaning as an additive metric that may describe the chromosome arm or other distinctive chromosome segment in terms of genetic recombination. It is a form of potential map length, comparable to, but numerically different from the regular map length. It is termed provisionally crossing-over potential.A chromosome with armsm andn with crossing-over potentials and will form ring bivalents with a frequency (1–e
–2).(1–e
–2); open bivalents with a frequency (1–e
–2).e
–2+(1–e
–2).e
–2; univalent pairs with a frequencye
–2.e
–2. Estimates of these frequencies yield equations from which and may be solved. In rye (Secale cereale) their ratio (q) is approximately two and differs from the mitotic arm length ratio of 1.4, indicating localization of chiasmata in the long arms.Graphs are given to show how, with constantq, the relation between the probabilitiesb
m
andb
n
of the two arms being bound changes with changing averageb.Data are presented on chiasma frequencies in M I, and compared with the frequencies expected in the absence of interference to give an impression of the degree of interference. Apparent fusion of chiasmata simulates interference. 相似文献
13.
Saccharomyces cerevisiae-based ethanol fermentations were conducted in batch culture, in a single stage continuous stirred tank reactor (CSTR), a multistage CSTR, and in a fermentor contaminated with Lactobacillus that corresponded to the first fermentor of the multistage CSTR system. Using a glucose concentration of 260 g l–1 in the medium, the highest ethanol concentration reached was in batch (116gl–1), followed by the multistage CSTR (106gl–1), and the single stage CSTR continuous production system (60gl–1). The highest ethanol productivity at this sugar concentration was achieved in the multistage CSTR system where a productivity of 12.7gl–1h–1 was seen. The other fermentation systems in comparison did not exceed an ethanol productivity of 3gl–1h–1. By performing a continuous ethanol fermentation in multiple stages (having a total equivalent working volume of the tested single stage), a 4-fold higher ethanol productivity was achieved as compared to either the single stage CSTR, or the batch fermentation. 相似文献
14.
The biological oceanography of waters adjacent to Australia's North West Cape (21° 49 S, 114° 14 E) was studied during the austral summers of 1997/98 and 1998/99. We measured egg production rate (EPR) by the small paracalanid copepods that dominated the calanoid community. Bottle incubation experiments were conducted at a shallow (20 m) station in the mouth of Exmouth Gulf, and at a shelf-break station (80 m). In 1997/98, we measured EPR by Paracalanus aculeatus, P. indicus, Acrocalanus gracilis and Bestiolina similis, but in 1998/99, we concentrated on P. indicus. Maximal observed EPRs by Paracalanus and Acrocalanus species were 30 eggs female–1 d–1, but B. similis attained only 17 eggs female–1 d–1. Sporadic measurements of EPR by P. aculeatus minor (maximum 4 eggs female–1 d–1) and Parvocalanus crassirostris ( 9 eggs female–1 d–1) were also made. However, maximal EPRs were seldom achieved and were often less than 10 eggs female–1 d–1. There was no difference between EPR of either P. indicus or B. similis in 1997/98 and 1998/99, despite differences in temperature. Trophic resources severely limit copepod egg production in this area. We suggest that variability and skewness of egg production data derived from individual incubations may be used to judge the degree of food limitation of the population and the variability in feeding success between individuals. The dominance of small copepods and the invariance in their EPR suggest that pulses in physical forcing and subsequent primary production will be severely damped by trophodynamic processes before reaching larval fish. 相似文献
15.
Internal motions of d-ribose selectively 2H-labeled at the 2 position were measured using solid state 2H NMR experiments. A sample of d-ribose-2
-d was prepared in a hydrated, non-crystalline state to eliminate effects of crystal-packing. Between temperatures of –74 and –60°C the C2–H2 bond was observed to undergo two kinds of motions which were similar to those of C2–H2/H2 found previously in crystalline deoxythymidine (Hiyama et al. (1989) J. Am. Chem. Soc., 111, 8609–8613): (1) Nanosecond motion of small angular displacement with an apparent activation energy of 3.6 ± 0.7 kcal mol–1, and (2) millisecond to microsecond motion of large amplitude with an apparent activation energy 4 kcal mol–1. At –74°C, the slow, large-amplitude motion was best characterized as a two-site jump with a correlation time on the millisecond time scale, whereas at –60°C it was diffusive on the microsecond time scale. The slow, large-amplitude motions of the C2–H2 bond are most likely from interconversions between C2-endo and C3-endo by way of the O4-endo conformation, whereas the fast, small-amplitude motions are probably librations of the C2–H2 bond within the C2-endo and C3-endo potential energy minima. 相似文献
16.
In Gyu Kim Il Lae Jung Tae Jeong Oh Kug Chan Kim Hae Won Shim 《Biotechnology letters》2002,24(16):1299-1305
Reactive oxygen species (ROS)-related oxidative damages have been implicated in a wide variety of the pathological processes such as atherosclerosis, inflammation and carcinogenesis. A polysaccharide-enriched fraction (PEF) was isolated from Duchesnea chrysantha, a herbaceous plant, and its antioxidant activity was demonstrated using several assay systems in vitro. The PEF effectively inhibited Cu2+-stimulated low density lipoprotein oxidation in a concentration-dependent way and retarded the conjugated diene formation with the enhancement of the lag phase during oxidation. An assay for DNA strand breaks showed that PEF strongly protected DNA against damage caused by UV or by OH or O2
– generated in the metal-catalyzed oxidation system. PEF effectively inhibited Nitroblue Tetrazolium reduction mediated by O2
– in a dose-dependent manner. It also competed with 2-deoxy-d-ribose in absorbing OH generated by -irradiation (600 Gy) and thus inhibited the formation malondialdehyde. In conclusion, these evidences indicate that PEF may act as an antioxidant to scavenge O2
–, OH or LO2 directly. Our findings suggest the possibility that it may play a role as a potential therapeutic antioxidant in treatment of oxidative damage-derived diseases. 相似文献
17.
Wheat for human consumption (140 samples) was collected after harvest from all regions of Bulgaria. The 1995 crop year was characterized by heavy rainfall in the spring and summer months. The internal mycoflora of wheat samples was dominated by Fusarium spp. and Alternaria spp., and storage fungi were rarely present. The samples were analysed for contamination with Fusarium mycotoxins deoxynivalenol (DON), 3-acetyldeoxynivalenol (3-AcDON), 15-acetyldeoxynivalenol (15-AcDON), T-2 Toxin (T-2), diacetoxyscirpenol (DAS), and zearalenone (ZEA), using enzyme immunoassay methods. DON and ZEA were the predominant toxins, with a contamination frequency of 67% and 69%, respectively. The average levels of these toxins in positive samples were 180 g/kg (DON) and 17 g/kg (ZEA), maximum concentrations were 1800 g kg–1 and 120 g kg–1, respectively. Acetyl derivatives of DON, namely 3-AcDON and 15-AcDON, were found in 2.1 % and 0.7% of the samples, at at maximum level of about 100 g kg–1. Only one sample was positive for T-2 (55 g/kg), DAS was not detected. This is the first report about the natural occurrence of a range of Fusarium mycotoxins in wheat for human consumption in Bulgaria.Abbreviations 3-AcDON
3-acetyldeoxynivalenol
- 15-AcDON
15-acetyldeoxynivalenol
- DAS
diacetoxyscirpenol
- DON
deoxynivalenol
- EIA
enzyme immunoassay
- T-2
T-2 toxin
- ZEA
zearalenone 相似文献
18.
Stephanos I. Grammatikos Papasani V. Subbaiah Thomas A. Victor William M. Miller 《Cytotechnology》1994,15(1-3):31-50
Fatty acids (FAs) have long been recognized for their nutritional value in the absence of glucose, and as necessary components of cell membranes. However, FAs have other effects on cells that may be less familiar. Polyunsaturated FAs of dietary origin (n–6 andn–3) cannot be synthesized by mammals, and are termed essential because they are required for the optimal biologic function of specialized cells and tissues. However, they do not appear to be necessary for normal growth and metabolism of a variety of cells in culture. The essential fatty acids (EFAs) have received increased attention in recent years due to their presumed involvement in cardiovascular disorders and in cancers of the breast, pancreas, colon and prostate. Manyin vitro systems have emerged which either examine the role of EFAs in human disease directly, or utilize EFAs to mimic thein vivo cellular environment. The effects of EFAs on cells are both direct and indirect. As components of membrane phospholipids, and due to their varying structural and physical properties, EFAs can alter membrane fluidity, at least in the local environment, and affect any process that is mediated via the membrane. EFAs containing 20 carbons and at least three double bonds can be enzymatically converted to eicosanoid hormones, which play important roles in a variety of physiological and pathological processes. Alternatively, EFAs released into cells from phospholipids can act as second messengers that activate protein kinase C. Furthermore, susceptibility to oxidative damage increases with the degree of unsaturation, a complication that merits consideration because lipid peroxidation can lead to a variety of substances with toxic and mutagenic properties. The effects of EFAs on cultured cells are illustrated using the responses of normal and tumor human mammary epithelial cells. A thorough evaluation of EFA effects on commercially important cells could be used to advantage in the biotechnology industry by identifying EFA supplements that lead to improved cell growth and/or productivity.Abbreviations AA
arachidonic acid (20 carbons: 4 double bonds,n–6)
- BHA
butylated hydroxyanisole
- BHT
butylated hydroxytoluene
- cAMP
cyclic adenosine monophosphate
- CHO
Chinese hamster ovary
- DAG
diacylglycerol
- DGLNA
dihomo--linolenic acid (203,n–6)
- DHA
docosahexaenoic acid (226,n–3)
- EFA
essential fatty acid
- EGF
epidermal growth factor
- EGFR
epidermal growth factor receptor
- EPA
eicosapentaenoic acid (205,n–3)
- FA
fatty acid
- FBS
fetal bovine serum
- GLNA
-linolenic acid (183,n–6)
- LA
linoleic acid (182,n–6)
- LNA
-linolenic acid (183,n–3)
- LT
leukotriene
- MDA
malondialdehyde
- NAD
nicotinamide adenine dinucleotide
- NDGA
nordihydroguaiaretic acid
- OA
oleic acid (181,n–9)
- PG
prostaglandin
- PKC
protein kinase C
- PUFA
polyunsaturated fatty acid
- SFM
serum-free medium
- TX
thromboxane 相似文献
19.
A suite of experiments are presented for the measurement of H–C, C–C, C–C and HN–N couplings from uniformly 15N, 13C labeled proteins. Couplings are obtained from a series of intensity modulated two-dimensional HN–N spectra equivalent to the common 1H–15N–HSQC spectra, alleviating many overlap and assignment issues associated with other techniques. To illustrate the efficiency of this method, H–C, C–C, and HN–N isotropic scalar couplings were determined for ubiquitin from data collected in less than 4.5 h, C–C data collection required 10 h. The resulting couplings were measured with an average error of ±0.06, ±0.05, ±0.04 and ±0.10 Hz, respectively. This study also shows H–C and C–C couplings, valuable because they provide orientation of bond vectors outside the peptide plane, can be measured in a uniform and precise way. Superior accuracy and precision to existing 3D measurements for C–C couplings and increased precision compared to IPAP measurements for HN–N couplings are demonstrated. Minor modifications allow for acquisition of modulated HN–C 2D spectra, which can yield additional well resolved peaks and significantly increase the number of measured RDCs for proteins with crowded 1H–15N resonances. 相似文献
20.
The extracellular surface of the-chain ofTorpedo california acetylcholine receptor (AChR) was mapped for regions that are accessible to binding with antibodies against a panel of synthetic overlapping peptides which encompassed the entire extracellular parts of the chain. The binding of the antipeptide antibodies to membrane-bound AChR (mbAChR) and to isolated, soluble AChR. was determined. The specificity of each antiserum was narrowed down by determining the extent of its cross-reaction with the two adjacent peptides that overlap the immunizing peptide. With mbAChR, high antibody reactivity was obtained with antisera against peptides1–16,89–104,158–174,262–276, and388–408. Lower, but significant, levels of reactivity were obtained with antibodies against peptides67–82,78–93,100–115, and111–126. On the other hand, free AChR bound high levels of antibodies against peptides34–49,78–93,134–150,170–186, and194–210. It also bound moderate levels of antibodies against peptides262–276 and388–408. Low, yet significant, levels of binding were exhibited by antibodies against peptides45–60,111–126, and122–138. These binding studies, which enabled a comparison of the accessible regions in mbAChR and free AChR, revealed that the receptor undergoes considerable changes in conformation upon removal from the cell membrane. The exposed regions found here are discussed in relation to the functional sites of AChR (i.e., the acetylcholine binding site, the regions that are recognized by anti-AChR antibodies, T-cells and autoimmune responses and the regions that bind short and long neurotoxins).Abbreviations used AChR
acetylcholine receptor
-
mbAChR
membrane-bound AChR
- BSA
bovine serum albumin
- BTX
-bungarotoxin
- EAMG
experimental autoimmune myasthenia gravis
- MG
myasthenia gravis
- PBS
0.15 MNaCl in 0.01 M sodium phosphate buffer, pH 7.2. 相似文献