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1.
《Bioscience, biotechnology, and biochemistry》2013,77(8):1946-1954
[2′,2′-2H2]-indole-3-acetic acid ([2′,2′-2H2]IAA) was prepared in an easy and efficient manner involving base-catalyzed hydrogen/deuterium exchange. 1-O-([2′,2′-2H2]-indole-3-acetyl)-β-D-glucopyranose, [2′,2′-2H2]-2-oxoindole-3-acetic acid, and 1-O-([2′,2′-2H2]-2-oxoindole-3-acetyl)-β-D-glucopyranose were also successfully synthesized from deuterated IAA, and effectively utilized as internal standards in the quantitative analysis of IAA and its metabolites in Arabidopsis thaliana by using liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS). The use of this technique shows that these metabolites were accumulated in the roots of Arabidopsis seedlings. Dynamic changes in the metabolites of IAA were observed in response to exogenous IAA, revealing that each metabolic action was regulated differently to contribute to the IAA homeostasis in Arabidopsis. 相似文献
2.
James P. Flinn Roger Murphy Jaroslav H. Boubliek Michael J. Lew Christine E. Writh James A. Angus 《Journal of peptide science》1995,1(6):379-384
The 27-residue polypeptide ω-conotoxin GVIA (ω-CgTx), from the venom of the cone shell Conus geographus, blocks N-type neuronal calcium channels. It contains three disulphide bridges. We reporte here the synthesis and biological characterization of a seires of analogues in which one disulphide has been replaced by substitution of appropriate Cys residues with Ser, viz. [Ser1,16]-ω-CgTx, [Ser8,19]-ω-CgTx, [Ser15,26]-ω-CgTx, [Ser16]-ω-CgTx8-27 and [Ser15]-ω-CgTx1-19. All syntheses were conducted manually using either Boc or Fmoc methodology. Deprotected peptides were oxidized to their bridged forms using either aerial oxidation or aqueous dimethyl sulphoxide. Peptides were purified using RP-HPLC, and their purity and identity were checked by RP-HPLC, capillary electrophoresis and mass spectrometry. Inhibition of neuronal N-type calcium channels was assessed as the inhibition of the twitch responses of rat vas deferens stimualted with single electrical pulses at 20 second intervals. None of these analogues was biologically active, suggesting that the disulphides play an important role in maintaining biological activity. 相似文献
3.
Dimitrios Tsikas Joachim Fauler Jürgen C. Frlich 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1992,574(2)
A simple and rapid method is described for the preparation of a stable isotope oxygen-18 labelled leukotriene E4 (LTE4). Oxygen-18 labelling of LTE4 methyl ester in oxygen-18 water catalysed by a pig liver esterase resulted in the incorporation of two oxygen-18 atoms in the carboxylic group of LTE4 to the extent of 89.8% ([18O2]LTE4) and one oxygen-18 atom to the extent of 9.4% ([16O18O]LTE4), with only 0.7% remaining unchanged ([16O2]LTE4). [18O2]LTE4 was found not to back-exchange following incubation in acidified urine (pH 4.0) at 4°C for up to 20 h. [18O2]LTE4 was demonstrated to be a useful internal standard in a method for the quantitative determination of LTE4 in human urine involving high-performance liquid chromatography and gas chromatography with negative-ion chemical ionization tandem mass spectrometry: the concentration of LTE4 in a 24-h urine sample of a healthy subject was determined to be 68.1 pg/ml. 相似文献
4.
Aoi Inosaki Akikazu Yasuda Tetsuro Shinada Yasufumi Ohfune Hideharu Numata Sakiko Shiga 《Comparative biochemistry and physiology. Part A, Molecular & integrative physiology》2010,155(2):190-199
Neuropeptides in neurosecretory cells of the pars intercerebralis (PI) and pars lateralis (PL) in the brain, and those in the corpus cardiacum–hypocerebral ganglion complex (CC-HG) and corpus allatum (CA) were examined by mass spectrometry and immunocytochemistry in adult females of the blowfly, Protophormia terraenovae. By using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), and electrospray ionization quadrupole orthogonal acceleration time-of-flight mass spectrometry (ESI-Q-Tof MS) and MS/MS, 4 peptides (including myosuppressin and SIFamide) were detected in the PI, 12 peptides (including [Arg7]-corazonin and [Arg7]-corazonin3–11) in the PL, 13 peptides (including myosuppressin, [Arg7]-corazonin and [Arg7]-corazonin3–11) in the CC-HG, and 6 peptides in the CA. MALDI-TOF MS analysis of each tissue or organ was made in about 20 flies under diapause-inducing (LD 12:12 at 20 °C) and diapause-averting conditions (LD 18:6 at 25 °C). These molecular ion peaks did not distinctively differ between diapause-inducing and diapause-averting conditions. A peptide with an m/z value at 1395.1 was purified from 240 brains and the 2nd–10th amino acids were sequenced as –YRKPPFNGS–, corresponding to a partial sequence of SIFamide. Only two pairs of somata in the PI were immunoreactive to antisera against SIFamide, which were local neurons widely extending fibers throughout the brain neuropils. 相似文献
5.
Polyoxometalate/laccase-mediated oxidative polymerization of catechol for textile dyeing 总被引:1,自引:0,他引:1
Kim S Silva C Evtuguin DV Gamelas JA Cavaco-Paulo A 《Applied microbiology and biotechnology》2011,89(4):981-987
The synergistic effect between polyoxometalates (POMs), namely K5[SiW11VVO40]·11H2O and H5[PMo10VV
2O40]·13H2O and laccase from ascomycete Myceliophthora thermophila has been employed for the first time in oxidative polymerization of catechol. Such a laccase-mediator system allowed the
formation of a relatively high molecular weight polycatechol as confirmed by size exclusion chromatography and electrospray
ionization mass spectrometry (ESI-MS) (3990 Da when using K5[SiW11VVO40]·11H2O and 3600 Da with H5[PMo10VV
2O40]·13H2O). The synthesized polymers were applied as dyes for the dyeing of flax fabrics. The color intensity of flax fabrics colored
with polymer solutions was evaluated by diffuse reflectance spectrophotometry via k/s measurements (+10% of fixation ratio). A new synthetic process allowed a dyeing polymer, provided upon flax coloration, better
color fixation and color resistance when compared to that obtained by conventional synthesis with laccase solely or with addition
of organic mediator (1-hydroxybenzotriazole). 相似文献
6.
Yoshihiko Shinohara Hiroshi Hasegawa Tomoyoshi Kaneko Yuka Tamura Takao Hashimoto Kimiyoshi Ichida 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2010,878(3-4):417-422
Homocysteine plays a key role in several pathophysiological conditions. To assess the methionine–homocysteine kinetics by stable isotope methodology, we developed a simultaneous quantification method of [2H7]methionine, [2H4]methionine, methionine, [2H4]homocysteine and homocysteine in rat plasma by gas chromatography–mass spectrometry (GC–MS). [13C]Methionine and [13C]homocysteine were used as analytical internal standards to account for losses associated with the extraction, derivatization and chromatography. For labeled and non-labeled homocysteine measurements, disulfide bonds between homocysteine and other thiols or proteins were reduced by dithiothreitol. The reduced homocysteine and methionine species were purified by cation-exchange chromatography and derivatized with isobutyl chlorocarbonate in water–ethanol–pyridine. Quantification was carried out by selected ion monitoring of the molecular-related ions of N(O,S)-isobutyloxycarbonyl ethyl ester derivatives on the chemical ionization mode. The intra- and inter-day precision of the assay was less than 6% for all labeled and non-labeled methionine and homocysteine species. The method is sensitive enough to determine pharmacokinetics of labeled methionine and homocysteine. 相似文献
7.
F. L. Booker 《Plant, cell & environment》2000,23(6):573-583
The objective of this study was to test whether elevated [CO2], [O3] and nitrogen (N) fertility altered leaf mass per area (LMPA), non‐structural carbohydrate (TNC), N, lignin (LTGA) and proanthocyanidin (PA) concentrations in cotton (Gossypium hirsutum L.) leaves and roots. Cotton was grown in 14 dm3 pots with either sufficient (0·8 g N dm ? 3) or deficient (0·4 and 0·2 g N dm ? 3) N fertilization, and treated in open‐top chambers with either ambient or elevated ( + 175 and + 350 μ mol mol ? 1) [CO2] in combination with either charcoal‐filtered air (CF) or non‐filtered air plus 1·5 times ambient [O3]. At about 50 d after planting, LMPA, starch and PA concentrations in canopy leaves were as much as 51–72% higher in plants treated with elevated [CO2] compared with plants treated with ambient [CO2], whereas leaf N concentration was 29% lower in elevated [CO2]‐treated plants compared with controls. None of the treatments had a major effect on LTGA concentrations on a TNC‐free mass basis. LMPA and starch levels were up to 48% lower in plants treated with elevated [O3] and ambient [CO2] compared with CF controls, although the elevated [O3] effect was diminished when plants were treated concurrently with elevated [CO2]. On a total mass basis, leaf N and PA concentrations were higher in samples treated with elevated [O3] in ambient [CO2], but the difference was much reduced by elevated [CO2]. On a TNC‐free basis, however, elevated [O3] had little effect on tissue N and PA concentrations. Fertilization treatments resulted in higher PA and lower N concentrations in tissues from the deficient N fertility treatments. The experiment showed that suppression by elevated [O3] of LMPA and starch was largely prevented by elevated [CO2], and that interpretation of [CO2] and [O3] effects should include comparisons on a TNC‐free basis. Overall, the experiment indicated that allocation to starch and PA may be related to how environmental factors affect source–sink relationships in plants, although the effects of elevated [O3] on secondary metabolites differed in this respect. 相似文献
8.
Summary Positive and negative ion FAB mass spectrometry were found to be useful for the structural analysis of phosphorylated peptides containing multiple O-phosphoseryl residues. The positive ion FAB mass spectra obtained for Ac-Ser(P)-Ser(P)-NHMe and Ac-Ser(P)-Ser(P)-Ser(P)-NHMe showed that -eliminative loss of H3PO4 from the Ser(P)-residue was a major event in the fragmentation of the two phosphopeptides and that successive losses of H3PO4 from the [M+H]+ ion occurred when the Ser(P)-cluster was located at the N-terminus. In contrast, the FAB mass spectrum of Ac-Glu-Ser(P)-Leu-Ser(P)-Ser(P)-Ser(P)-Glu-Glu-NHMe showed only a single loss of H3PO4 from the [M+H]+ ion, with further losses of H3PO4 from internal Ser(P)-residues only occurring when fragmentation of the parent phosphopeptide generated daughter fragments that contained (part of) an N-terminal Ser(P)-residue. Negative ion FAB mass spectrometry also proved useful for the structural analysis of the three Ser(P)-peptides and showed high-intensity [M-H]- ions along with minor [M-H-80]- fragment ions.Abbreviations Ac
acetyl
- Ala
dehydroalanyl
- FAB-MS
fast atom bombardment mass spectrometry
- LSIMS
liquid secondary ion mass spectrometry
- NHMe
N-methylamide
- Ser(P)
O-phosphoseryl
- Thr(P)
O-phosphothreonyl 相似文献
9.
A study of derivatives of N6-(isopent-2-enyl)adenine formed by substitution at N-9 indicated that sensitivity of detection by chemical ionization mass spectrometry was maximized by a pentafluorobenzyl substituent and negative ion monitoring. O-t-Butyldimethylsilyl-9-pentafluorobenzyl derivatives of zeatin (Z),cis-zeatin (cis-Z), and dihydrozeatin (DZ) were characterized by mass spectrometry. A procedure was based on these stable derivatives and negative ion chemical ionization mass spectrometry for quantification of zeatin and dihydrozeatin in plant tissue.For part VI, see Letham and Singh (1989). 相似文献
10.
Naohito Takeda Ken-ichi Harada Makoto Suzuki Akira Tatematsu Nobuhiro Hirai Koichi Koshimizu 《Bioscience, biotechnology, and biochemistry》2013,77(9):2295-2300
The use of desorption chemical ionization (D/CI) mass spectrometry for the structural characterization of the abscisic acid (ABA)-conjugated metabolites, abscisic acid-γ-d-glucosyl ester (ABAGE), 4′-O-dihydrophaseic acid-γ-d-glucoside (DPAGS) and γ-hydroxy-γ-methylglutaryl-hydroxyabscisic acid (HMG-HOABA), was studied. The effects of the D/CI source temperature on the spectral features are described. Enhanced quasi-molecular ion intensities (e.g., [M·NH4]+) were observed in the D/CI(NH3) spectrum at a low source temperature (170°C). When a higher source temperature (250°C) was used, more extensive fragmentation occurred, and structurally diagnostic fragment ions appeared in the spectra. The spectra obtained at two degrees of source temperature were complementary to each other for the structural characterization. 相似文献
11.
The role of light in soybean seed filling metabolism 总被引:2,自引:0,他引:2
Doug K. Allen John B. Ohlrogge Yair Shachar-Hill 《The Plant journal : for cell and molecular biology》2009,58(2):220-234
Soybean (Glycine max) yields high levels of both protein and oil, making it one of the most versatile and important crops in the world. Light has been implicated in the physiology of developing green seeds including soybeans but its roles are not quantitatively understood. We have determined the light levels reaching growing soybean embryos under field conditions and report detailed redox and energy balance analyses for them. Direct flux measurements and labeling patterns for multiple labeling experiments including [U‐13C6]‐glucose, [U‐13C5]‐glutamine, the combination of [U‐14C12]‐sucrose + [U‐14C6]‐glucose + [U‐14C5]‐glutamine + [U‐14C4]‐asparagine, or 14CO2 labeling were performed at different light levels to give further insight into green embryo metabolism during seed filling and to develop and validate a flux map. Labeling patterns (protein amino acids, triacylglycerol fatty acids, starch, cell wall, protein glycan monomers, organic acids), uptake fluxes (glutamine, asparagine, sucrose, glucose), fluxes to biomass (protein amino acids, oil), and respiratory fluxes (CO2, O2) were established by a combination of gas chromatography‐mass spectrometry, 13C‐ and 1H‐NMR, scintillation counting, HPLC, gas chromatography‐flame ionization detection, C:N and amino acid analyses, and infrared gas analysis, yielding over 750 measurements of metabolism. Our results show: (i) that developing soybeans receive low but significant light levels that influence growth and metabolism; (ii) a role for light in generating ATP but not net reductant during seed filling; (iii) that flux through Rubisco contributes to carbon conversion efficiency through generation of 3‐phosphoglycerate; and (iv) a larger contribution of amino acid carbon to fatty acid synthesis than in other oilseeds analyzed to date. 相似文献
12.
Baterial lipase from Staphylococcus carnosus (pLipMut2) has been immobilized on various supports in order to determine a suitable immobilization technique in terms of activity and stability, when utilized for the hydrolysis of tributyrin. The hydrophobic materials PBA Eupergit and PBA Eupergit 250L prooved to be appropriate supports, when the enzyme was crosslinked with glutaraldehyde after adsorption. No desorption of the immobilized enzyme occured during operation. The pore size of the support has a strong effect on the activity but does not influence stability.The initial activity for immobilized and soluble lipase is found to follow the Arrhenius equation at low temperature, where mass transfer does not affect reaction kinetics. Activation energies for soluble and immobilized lipase were evaluated to be 21.7 kJ mol–1 and 60.8 kJ mol–1, respectively.Operational stability was studied in a packed bed recirculation reactor. Thermal desactivation followed first order kinetics with a half-life of 1340 h at 10°C. Model calculations for productivity showed, that optimal temperatures for high productivity are well below the temperature of maximal activity.List of Symbols
E
a
[kJ mol–1]
activation energy
-
E
d
[kJ mol–1]
activation energy of desactivation
-
H [–]
half-number
-
k
d
[h–1]
desactivation constant
-
k
d, [h–1]
constant
-
k
N
[–]
desactivation constant (number)
-
N [–]
number of runs
-
p [mol dm–3]
productivity
-
t [h]
time
-
t
0.5 [h]
half-life
-
T [K]
absolute temperature
-
V [U ml–1]
activity
- V(N) [Uml–1]
activity exhibited in the n-th run
-
V
s,O [U ml–1]
initial activity of supernatant
-
V
s, [U ml–1]
activity of supernatant after immobilization
-
V
O [U ml–1]
initial activity
-
V
[U ml–1]
constant
-
imm
[–]
activity yield
-
[ml ml–1]
ratio of volume of support to volume of supernatant
Financial support of this work by the Deutsche Forschungsgemeinschaft (SFB 145, A15) is gratefully acknowledged. 相似文献
13.
C. Allievi P. Dostert M. Strolin Benedetti 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1991,568(2)
The urine concentrations of free salsolinol were determined in six healthy volunteers, using a gas chromatographic—mass spectrometric method with electron-capture negative-ion chemical ionization after derivatization with pentafluoropropionyl anhydride. The sensitivity of this method allows the quantification of salsolinol concentrations of 0.55 pmol/ml. The synthesis of [2H4]salsolinol from dopamine and [2H4]acetaldehyde via a Pictet—Spengler condensation is described; [2H4]salsolinol was used as the internal standard for salsolinol quantification. The urine concentrations of free salsolinol ranged from ca. 1 to 6 pmol/ml. 相似文献
14.
J V Pothuluri J P Freeman P P Fu C E Cerniglia 《Journal of industrial microbiology & biotechnology》1999,22(1):52-57
Biotransformation of 1-nitrobenzo[e]pyrene (1-nitro-BeP), an environmental pollutant derived from the nitration of a non-carcinogen, benzo[e]pyrene, was studied using the fungus Cunninghamella elegans ATCC 36112. After 72 h incubation, 89% of 1-nitro-[3H]BeP added had been metabolized to two major metabolites. These metabolites were separated by reversed-phase high performance
liquid chromatography and identified by 1H NMR, UV-visible, and mass spectral techniques as 1-nitro-6-benzo[e]pyrenylsulfate and 1-nitrobenzo[e]pyrene 6-O-β-glucopyranoside. Comparison of the fungal metabolism patterns of 1-nitro-BeP and BeP indicates that the nitro group at the C-1 position of BeP altered the regioselectivity of metabolism.
Received 29 September 1998/ Accepted in revised form 15 December 1998 相似文献
15.
《Journal of receptor and signal transduction research》2013,33(1-6):315-329
AbstractExcised dorsal skin of Anolis carolinensis was exposed to high intensity UV-irradiation in the presence of different photoreactive α-MSH derivatives. The resulting covalent binding of the hormone to its receptor induced irreversible pigment dispersion. The duration of the longlasting response depended on the type and length of irradiation; it was maximal after two 5 min irradiation phases with a light intensity of ~180 mW/cm2 and a spectrum from 310 to 550 nm, fresh hormone being added after the first phase. [Nα-(4-Azidophenyl-acetyl-serine1]-α-MSH (I), [2′-(2-nitro-4-azidophenylsulphenyl)-tryptophan9]-α-MSH (II) and [p-azidophenylalanine13]-α-MSH (III) all inserted into the receptor to about the same extent, as judged from the persistence of the longlasting signal. In contrast, [D-alanine1, p-azidophenylalanine2, norvaline4]-α-MSH (IV) and [Nα-(4-azidophenylacetyl)-serine1, leucine9]-α-MSH (V) gave much less insertion and [leucine9, p-azidophenylalanine13]-α-MSH (VI) hardly any insertion when applied in the same relative excess (5-fold the concentration inducing a maximal response). Covalent attachment of the cleavable photolabel [Nα-(4-azidophenyl)-1, 3′-dithio-propionyl-serine1]-α-MSH (VII) and subsequent washing of the skin in buffer containing 1% β-mercaptoethanol released the peptide from the receptor. Insertion of the C-terminal photolabel [p-azidophenylalanine13]-α-MSH was reduced by the weak antagonist H-Phe-Ala-Trp-Gly-Gly-Pro-Val-NH2. These experiments prove that hormone receptors can be covalently labelled in tissue with very limited light transparency. 相似文献
16.
To model the mononuclear FeIII-OOH species identified in the catalytic cycle of the anticancer drug bleomycin, the iron chemistry of the pentadentate ligand N-[bis(2-pyridylmethyl)aminoethyl]pyridine-2-carboxamide (H-PaPy3) has been investigated. The complex [FeIII(PaPy3)OCH3](ClO4) was reacted with H2O2 to form a red species (max=480 nm, =1800 M–1 cm–1) with an S=1/2 EPR signal at g=2.25, 2.17, and 1.95. This species has been identified by electrospray ionization mass spectrometry as [FeIII(PaPy3)OOH](ClO4) and further characterized by resonance Raman and EXAFS analysis. The decomposition of this intermediate leads to the modification of the ligand, as revealed by 1H NMR. One hydrogen atom is substituted by a solvent-derived methoxy group. The substitution at this site is a result of the two-electron oxidation of the ligand following the heterolytic cleavage of the O–O bond of the FeIII-OOH species. This is a plausible mechanism to rationalize related ligand modifications that have been proposed in the decay of activated bleomycin.Abbreviations ABLM
activated bleomycin
- BLM
bleomycin
- ESI-MS
electrospray ionization mass spectrometry
- EXAFS
extended X-ray absorption fine structure
- H-PaPy3
N-[bis(2-pyridylmethyl)aminoethyl]pyridine-2-carboxamide 相似文献
17.
Jin YX Shi LH Yoo HS Lee YM Kihara A Igarashi Y So HY Yim YH 《Analytical biochemistry》2008,380(1):35-40
D-erythro-Sphingosine is known to be phosphorylated by sphingosine kinase to yield sphingosine-1-phosphate. With the importance of sphingosine-1-phosphate in biological functions being made evident by recent research, a selective and convenient method of assay to measure sphingosine kinase activity is required. Here we developed a new sphingosine kinase assay using murine teratocarcinoma mutant F9-12 cells and electrospray ionization tandem mass spectrometry (ESI–MS/MS) with direct infusion. Sphingosine-1-phosphate in the crude extract of enzyme reaction mixture was selectively characterized and quantitated using precursor ion scanning for [PO3]- in the negative electrospray ionization mode. The method was successfully validated for an activator and an inhibitor of sphingosine kinase. Direct quantitation of S1P without the use of radioactive reagents, chemical derivatization, and extensive chromatographic separation enables simplified assay for sphingosine kinase activity at the cellular system level, and the use of a structural analog as an internal standard provides robustness to the assay. 相似文献
18.
Maryanne R. Hughes David Kojwang Tania Zenteno-Savin 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1992,162(7):625-631
Summary The intestinal caeca reabsorb urinary sodium chloride (NaCl) and water (Rice and Skadhauge 1982). Free water may be generated if the reabsorbed NaCl is secreted via salt gland secretion (Schmidt-Nielsen et al. 1958). Therefore ceacal ligation should (a) reduce hingut NaCl and water reabsorption, (b) enhance the increase in plasma osmolality during saline acclimation, and (c) affect drakes more than ducks. Twelve Pekin drakes and 13 Pekin ducks, Anas platyrhynchos, were caecally ligated or sham operated before acclimation to 450 mmol · 1 NaCl. Body mass, hematocrit, plasma osmolality, and inonic concentrations of plasma, cloacal fluid, and salt gland secretion were measured after each increase in drinking water salinity. Osmoregulatory organ masses were determined. Caecal ligation did not effect plasma osmolality or ion concentrations of plasma, cloacal fluid, or salt gland secretion, but reduced salt gland size in ducks. Drakes and ducks drinking fresh water had the same hematocrit, plasma osmolality, and plasma concentrations of Na+ and Cl–. In both sexes exposure to 75 mmol · 1-1 NaCl significantly decreased plasma [Na+] and doubled cloacal fluid [Na+]. Exposure to 450 mmol · 1-1 NaCl decreased body mass and increased hematocrit, plasma [Na+], [Cl–], and plasma osmolality (more in drakes than in ducks); cloacal fluid osmolality nearly doubled compared to freshwater-adapted ducks, due mainly to osmolytes other than Na+ and Cl–. The [Cl–] in salt gland secretion only slightly exceeded drinking water [Cl–].Abbreviations
AVT
antiduretic hormone
-
CF
cloacal fluid
-
ECFV
extraoellular fluid volume
-
FW
freshwater acclimated
-
Hct
hematocrit
-
MDWE
mean daily water flux
-
[Na
+]cf
cloacal fluid sodium concentration
-
[Na
+]pl
plasma sodium concentration
-
Osm
cf
cloacal fluid osmolality
-
Osm
pl
plasma osmolality
-
SGS
salt gland secretion
-
TBW
total body water 相似文献
19.
Summary Mixtures of cyclic peptides, formed by head-to-tail cyclizations of side-chain resin-bound linear sequences, have been prepared using solid-phase synthesis. Fast atom bombardment mass spectrometry of cyclic peptides with various metal ions can reveal preferred modes of host-guest patterns, albeit in a nonquantitative manner. This approach could prove useful for more rapid screening of potential peptide ionophores. A cyclic heptapeptide with a dipeptide tail proved to be a particularly effective host for a Ca2+ ion; in a small three-component mixture, cyclo[Gly-Asp-d-Pro-Xxx-Asp-d-Pro-Asp(Aca-Phe-NH2)], binding to Ca2+ varied from Xxx=N-MeAla>GlySar. In a 15-component mixture, cyclo[Pro-Xxx-Asn-Pro-Xxx-Asn] where Xxx=Ala, Glu, Leu, Lys or Phe, there were no significant differences with respect to binding to metal ions. We believe this to be the first reported use of cyclic peptide libraries for screening metal ions to discern host-guest relationships.Abbreviations Aca
aminocaproic acid
- Boc
tert-butyloxycarbonyl
- BOP
benzotriazolyloxy-tris(dimethylamino)phosphonium hexafluorophosphate
- DCM
dichloromethane
- DIEA
diisopropylethylamine
- DMF
N,N-dimethylformamide
- ESI
electrospray ionization
- FABMS
fast atom bombardment mass spectrometry
- pMBHA
4-methylbenzhydrylamine
- TFA
trifluoroacetic acid
This paper is based on a presentation given at the Symposium on Peptide Structure and Design as part of the 31st Annual ACS Western Regional Meeting held in San Diego, CA, USA, October 18–21, 1995. 相似文献
20.
《Nucleosides, nucleotides & nucleic acids》2013,32(1-2):59-75
The nucleophilic addition–elimination reaction of 2′,3′,5′-tri-O-acetyl-2-fluoro-O 6-[2-(4-nitrophenyl)ethyl]inosine (8) with [15N]benzylamine in the presence of triethylamine afforded the N 2-benzyl[2-15N]guanosine derivative (13) in a high yield, which was further converted into the N 2-benzoyl[2-15N] guanosine derivative by treatment with ruthenium trichloride and tetrabutyl-ammonium periodate. A similar sequence of reactions of 2′,3′,5′-tri-O-acetyl-2-fluoro-O 6-[2-(methylthio)ethyl]inosine (9) and the 6-chloro-2-fluoro-9-(β-D-ribofuranosyl)-9H-purine derivative (11), which were respectively prepared from guanosine, with potassium [15N]phthalimide afforded the N 2-phthaloyl [2-15N]guanosine derivative (15; 62%) and 9-(2,3,5-tri-O-acetyl-β-D-ribofuranosyl)-6-chloro-2-[15N]phthalimido-9H-purine (17; 64%), respectively. Compounds 15 and 17 were then efficiently converted into 2′,3′,5′-tri-O-acetyl[2-15N]guanosine. The corresponding 2′-deoxy derivatives (16 and 18) were also synthesized through similar procedures. 相似文献