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1.
The enzyme catalyzing the reduction of sulfite by reduced benzyl viologen (BVH) was partially purified and characterized from two strains of wine yeasts, a sulfite-producing strain and a non-producing strain.Both enzymes showed corresponding features in pH-optima, optima of buffer and benzyl viologen concentrations.The enzymes did not catalyze the reduction of nitrite by reduced viologen dyes, but the reduction of sulfite was uncompetitively inhibited by nitrite. Compounds of sulfur metabolism such as sulfate, thiosulfate, cysteine, serine and methionine did not influence the activity of either of the enzymes. The main differences between the two enzymes exist in the specific activities in crude extracts, the K
m
-values for sulfite, substrate inhibition rates, and localization in different fractions during (NH4)2SO4 precipitation. The specific activity in crude extracts of the sulfite-producing strain (0.052 moles S2- x min-1 x mg-1) was about three fold higher than that of the non-producing strain (0.0179 moles S2- x min-1 x mg-1). On the other hand the sulfite-producing strain had a higher K
m
-value for sulfite (2×10-3 M) and was more strongly inhibited by the substrate than the non-producing strain (6×10-3 M). 相似文献
2.
Cells of the phototrophic bacterium Chromatium vinosum strain D were shown to contain a siroheme sulfite reductase after autotrophic growth in a sulfide/bicarbonate medium. The enzyme could not be detected in cells grown heterotrophically in a malate/sulfate medium. Siroheme sulfite reductase was isolated from autotrophic cells and obtained in an about 80% pure preparation which was used to investigate some molecular and catalytic properties of the enzyme. It was shown to consist of two different types of subunits with molecular weights of 37,000 and 42,000, most probably arranged in an 44-structure. The molecular weight of the native enzyme was determined to 280,000, 51 atoms of iron and 47 atoms of acid-labile sulfur were found per enzyme molecule. The absorption spectrum indicated siroheme as prosthetic group; it had maxima at 280 nm, 392 nm, 595 nm, and 724 nm. The molar extinction coefficients were determined as 302×103 cm2xmmol-1 at 392 nm, 98×103 cm2 xmmol-1 at 595 nm and 22×103 cm2x-mmol-1 at 724 nm. With reduced viologen dyes as electron donor the enzyme reduced sulfite to sulfide, thiosulfate, and trithionate. The turnover number with 59 (2 e-/enzyme moleculexmin) was low. The pH-optimum was at 6.0. C. vinosum sulfite reductase closely resembled the corresponding enzyme from Thiobacillus denitrificans and also desulfoviridin, the dismilatory sulfite reductase from Desulfovibrio species. It is proposed that C. vinosum catalyses anaerobic oxidation of sulfide and/or elemental sulfur to sulfite in the course of dissimilatory oxidation of reduced sulfur compounds to sulfate.Non-common abbreviations APS
adenylyl sulfate
- SDS
sodium dodecyl sulfate 相似文献
3.
Ewa J. Kurek 《Archives of microbiology》1985,143(3):277-282
An enzymatic complex from Rhodotorula was characterized and it was indicated that it possessed thiosulfate-oxidizing activity, forming tetrathionate as well as sulfite oxidase activity. Both activities coupled with ferricyanide and native cytochrome c but no with mammalian cytochrome c. Activities of these enzymes were inhibited by thiol inhibitors. Chelating agents did not affect thiosulfate oxidizing activity and only moderately inhibited sulfite oxidase. Both activities disappeared after treatment with proteolytic enzymes or sodium deoxycholate which indicates an essential role played not only by protein but also by phospholipids in the enzymatic activity of the complex. Thiosulfate oxidizing enzyme had a K
m for thiosulfate of 0.16 mM with ferricyanide as electron acceptor and of 14 M with native cytochrome c and of 0.34 mM for ferricyanide. Optimum pH for this activity was 7.8. Other properties of this enzyme were similar to those of thiobacilli and heterotrophic bacteria. The activity of sulfite oxidase was inhibited by 50% with 10 M AMP. The K
m values of this enzyme were 1 mM with ferricyanide as electron acceptor and 60 M with native cytochrome c for sulfite and 0.42 mM for ferricyanide. The enzyme did not show a specific optimum pH value with ferricyanide as electron acceptor. However, with native cytochrome c optimum pH was 7.8 for its activity. In many properties the sulfite oxidase from Rhodotorula was similar to the enzyme from Thiobacillus ferrooxidans, T. concretivorus, T. thioparus and T. novellus.Abbreviations CSH
reduced glutathion
- APS
reductase, adenosine-S-phosphosulfate reductase
- pHMB
p-hydroxymercuribenzoate
- NEM
N-ethylmalcimide
- TCA
trichloroacetic acid
- PPO
2,5-diphenyloxazole
- POPOP
2,2-p-phenylen-bis 5-phenyloxazol 相似文献
4.
The localization of the dissimilatory sulfite reductase in Desulfovibrio desulfuricans strain Essex 6 was investigated. After treatment of the cells with lysozyme, 90% of the sulfite reductase activity was found in the membrane fraction, compared to 30% after cell rupture with the French press. Sulfite reductase was purified from the membrane (mSiR) and the soluble (sSiR) fractiion. On SDS-PAGE, both mSiR and sSiR exhibited three bands at 50, 45 and 11 kDa, respectively. From their UV/VIS properties (distinct absorption maxima at 391, 410, 583, 630 nm, enzymes as isolated) and the characteristic red fluorescence in alkaline solution, mSiR and sSiR were identified as desulfoviridin. Sulfite reductase (HSO3
-H2S) activity was reconstituted by coupling of mSiR to hydrogenase and cytochrome c
3 from D. desulfuricans. The specific activity of mSiR was 103 nmol H2 min-1 mg-1, and sulfide was the major product (72% of theoretical yield). No coupling was found with sSiR under these conditions. Furthermore, carbon monoxide was used to diferentiate between the membrane-bound and the soluble sulfite reductase. In a colorimetric assay, with photochemically reduced methyl viologen as redox mediator, CO stimulated the activity of sSiR significantly. CO had no effect in the case of mSiR. These studies documented that, as isolated, both forms of sulfite reductase behaved differently in vitro. Clearly, in D. desulfuricans, the six electron conversion HSO3
-H2S was achieved by a membranebound desulfoviridin without the assistance of artificial redox mediators, such as methyl viologen.Abbreviations
SiR
sulfite reductase
-
mSiR
sulfite reductase purified from membranes
-
sSiR
sulfite reductase purified from the soluble fraction
Enzymes Sulfite reductase, EC 1.8.99.1 Cytochrome c
3 hydrogenase, EC 1.12.2.1 相似文献
5.
The localization of enzymes of assimilatory sulfate reduction was examined in roots of 5-d-old pea (Pisum sativum L.) seedlings. During an 8-h period, roots of intact plants incorporated more label from 35SO
4
2-
in the nutrient solution into the amino-acid and protein fractions than shoots. Excised roots and roots of intact plants assimilated comparable amounts of radioactivity from 35SO
4
2-
into the amino-acid and protein fractions during a 1-h period, demonstrating that roots of pea seedlings at this stage of development were not completely dependent on the shoots for reduced sulfur compounds. Indeed, these roots contained activities of ATP-sulfurylase (EC 2.7.7.4), adenosine 5-phosphosulfate sulfotransferase, sulfite reductase (EC 1.8.7.1) and O-acetyl-l-serine sulfhydrylase (EC 4.2.99.8) at levels of 50, 30, 120 and 100%, respectively, of that in shoots. Most of the extractable activity of adenosine 5-phosphosulfate sulfotransferase was detected in the first centimeter of the root tip. Using sucrose density gradients for organelle separation from this part of the root showed that almost 40% of the activity of ATP-sulfurylase, adenosine 5-phosphosulfate sulfotransferase and sulfite reductase banded with the marker enzyme for proplastids, whereas only approximately 7% of O-acetyl-l-serine sulfhydrylase activity was detected in these fractions. Because their distributions on the gradients were very similar to that of nitrite reductase, a proplastid enzyme, it is concluded that ATP-sulfurylase, adenosine 5-phosphosulfate sulfotransferase and sulfite reductase are also exclusively or almost exclusively localized in the proplastids of pea roots. O-Acetyl-l-serine sulfhydrylase is predominantly present in the cytoplasm.Abbreviation APSSTase
adenosine 5-phosphosulfate sulfotransferase 相似文献
6.
Bearne SL White RL MacDonnell JE Bahrami S Grønlund J 《Molecular and cellular biochemistry》2001,221(1-2):117-126
Methylaspartase (EC 4.3.1.2) was purified 20fold in 35% yield from Fusobacterium varium, an obligate anaerobe. The purification steps included heat treatment, fractional precipitation with ammonium sulfate and ethanol, gel filtration, and ion exchange chromatography on DEAESepharose. The enzyme is dimeric, consisting of two identical 46 kDa subunits, and requires Mg2+ (Km = 0.27 ± 0.01 mM) and K+ (Km = 3.3 ± 0.8 mM) for maximum activity. Methylaspartasecatalyzed addition of ammonia to mesaconate yielded two diastereomeric amino acids, identified by HPLC as (2S,3S)3methylaspartate (major product) and (2S,3R)3methylaspartate (minor product). Optimal activity for the deamination of (2S,3S)3methylaspartate (Km = 0.51 ± 0.04 mM) was observed at pH 9.7. The Nterminal protein sequence (30 residues) of the F. varium enzyme is 83% identical to the corresponding sequence of the clostridial enzyme. 相似文献
7.
Growth yields and growth rates of Desulfovibrio vulgaris (Marburg) growing on hydrogen plus sulfate and hydrogen plus thiosulfate as the sole energy sources 总被引:13,自引:0,他引:13
Desulfovibrio vulgaris (Marburg) was grown on H2 plus sulfate and H2 plus thiosulfate as the sole energy sources and acetate plus CO2 as the sole carbon sources. Conditions are described under which the bacteria grew exponentially. Specific growth rates () and molar growth yields (Y) at different pH were determined. and Y were found to be strongly dependent on the pH. Highest growth rates and molar growth yields were observed for growth on H2 plus sulfate at pH 6.5 (=0.15h-1; Y
SO
4
2-
=8.3g·mol-1) and for growth on H2 plus thiosulfate at pH 6.8 (=0.21h-1; Y
S
2O
3
2
=16.9g·mol-1).The growth yields were found to increase with increasing growth rates: plots of 1/Y versus 1/ were linear. Via extrapolation to infinite growth rates a Y
SO4
2-
/max of 12.2g·mol-1 and a YS2O
3
2-
/max of 33.5g·mol-1 was obtained.The growth yield data are interpred to indicate that dissimilatory sulfate reduction to sulfide is associated with a net synthesis of 1 mol of ATP and that near to 3 mol of ATP are formed during dissimilatory sulfite reduction to sulfide. 相似文献
8.
Tom S. Chen Byron H. Arison Vincent P. Gullo Edward S. Inamine 《Journal of industrial microbiology & biotechnology》1989,4(3):231-237
Summary The biosynthesis of avermectins was studied further inStreptomyces avermitilis MA5502 by feeding experiments with labeled precursors.13C-NMR analysis of the compounds biosynthesized from [2-13C]acetate, [1,2-13C2]acetate, [3-13C]propionate and [2,3-13C2]propionate confirmed that the aglycone of avermectins is made from seven intact acetate and five propionate units. Feeding experiments with [1-13C]2-methylbutyrate and [1-13C]isobutyrate have shown that 2-methylbutyrate and isobutyrate are immediate precursors of the starter units of the polyketide chains of avermectin a and b components, respectively. The3H/14C doublelabeling experiments suggest that the two oleandrose moieties are derived from glucose. 相似文献
9.
Jo Anne Stubbe 《Molecular and cellular biochemistry》1983,50(1):25-45
Summary Ribonucleotide reductase from L. leichmmannii catalyzes cleavage of the carbon cobalt bond of AdoCbl homolytically in a kinetically competent fashion. This cleavage triggers a chain of events which results in cleavage of the 3C-H bond of the nucleotide substrate followed by cleavage of the 2 carbon hydroxyl bond. Involvement of a radical cation has been suggested as a possible mechanism by which this unusual reduction reaction might occur. Furthermore, cleavage of the 3 carbon hydrogen bond of [3-3H]NTP resulted in no 3H release to solvent and no 3H recovered in AdoCbl. These results were interpreted to mean that in this system AdoCbl does not serve as a H abstractor, but rather as a radical chain initiator. A protein residue on the RTPR is postulated to carry out the actual H abstraction from the substrate.These results and the conclusions drawn from them are further supported by recent experiments using [3-3H]CIUTP. Incubation of RTPR with [3-3H]CIUTP resulted in release of 3H2O, uracil, PPPi, formation of Coll and 5 deoxyadenosine. The 3H2O release confirms the enzyme's ability to cleave the 3C-H bond of a nucleotide analog. Furthermore, little if any 3H was recovered in the 5 deoxyadenosine and the rate of 3H2O release from [33H]CIUTP was 12 times faster than the rate of 3H2O release from [5-3H]AdoCbl. These observations support the conclusions drawn from data with the normal substrate; ie, AdoCbl serves as a radical chain initiator rather than a direct H abstractor from substrate. 相似文献
10.
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
11.
Irina B. Naumova Nailya A. Yanushkene Galina M. Streshinskaya Alexander S. Shashkov 《Archives of microbiology》1990,154(5):483-488
The cell wall of Actinoplanes philippinesis VKM Ac-647 harbours several carbohydrate-containing anionic polymers. (1) The main polymer of the wall is of a poly(glycosylglycerol phosphate) nature. Its monomeric units — O--d-mannopyranosyl-(14)--d-galactopyranosyl-(11)-glycerol monophosphates — are connected by phosphodiester bonds involving the hydroxyl groups at glycerol C3 and galactose C6. There also are chains without mannosyl substitutents. The teichoic acid structure has been established by chemical analysis and with 1H and 13C NMR spectroscopy. This is the first finding of a teichoic acid with mannosyl residues in a bacterial cell wall. (2) The phosphorylated mannan contains mannose and 2-O-methylmannose. Its core chain has -1,2; -1,3; and -1,6 substitutions as revealed by 13C NMR spectroscopy.The peptide unit of the peptidoglycan contains no l-alanine, instead of which position 1 is occupied by glycine; and diaminopimelic acid is represented, besides its meso- (or DD) form, by small amounts of its LL isomer.Abbreviations Gro
glycerol
- Gro2P
glycerol-2 phosphate
- APT
attached-proton-test
- Ptot
total content of phosphorus
- Plab
phosphorus mineralized in 7 min at 100°C
- PNA
phosphorus of nucleic acids
- Pstab
stable phosphorus
- T
trace amounts 相似文献
12.
Summary In order to study some internal dynamic processes of the lac operator sequence, the 13C-labeled duplex 5d(C0G1C2T3C4A5C6A7A8T9T10) · d(A10A9T8T7G6T5G4A3G2C1G0)3 was used. The spreading of both the H1 and C1 resonances brought about an excellent dispersion of the 1H1-13C1 correlations. The spinlattice relaxation parameters R(Cz), R(Cx,y) and R(HzCz) were measured for each residue of the two complementary strands, except for the 3-terminal residues which were not labeled. Variation of the relaxation rates was found along the sequence. These data were analyzed in the context of the model-free formalism proposed by Lipari and Szabo [(1982) J. Am. Chem. Soc., 104, 4546–4570] and extended to three parameters by Clore et al. [(1990) Biochemistry, 29, 7387–7401; and (1990) J. Am. Chem. Soc., 112, 4989–4991]. A careful analysis using a least-squares program showed that our data must be interpreted in terms of a three-parameter spectral density function. With this approach, the global correlation time was found to be the same for each residue. All the C1-H1 fragments exhibited both slow (s = 1.5) and fast (f = 20 ps) restricted libration motions (S
inf2
sups
=0.74 to 1.0 and S
inf2
supf
=0.52 to 0.96). Relaxation processes were described as governed by the motion of the sugar relative to the base and in terms of bending of the whole duplex. The possible role played by the special structure of the AATT sequence is discussed. No evident correlation was found between the amplitude motions of the complementary residues. The 5-terminal residues showed large internal motions (S2=0.5), which describe the fraying of the double helix. Global examination of the microdynamical parameters S
inf2
supf
and S
inf2
sups
along the nucleotide sequence showed that the adenine residues exhibit more restricted fast internal motions (S
inf2
supf
=0.88 to 0.96) than the others, whereas the measured relaxation rates of the four nucleosides in solution were mainly of dipolar origin. Moreover, the fit of both R(Cz) and R(HzCz) experimental relaxation rates using an only global correlation time for all the residues, gave evidence of a supplementary relaxation pathway affecting R(Cx,y) for the purine residues in the (53) G4A3 and A10A9T8T7 sequences. This relaxation process was analyzed in terms of exchange stemming from motions of the sugar around the glycosidic bond on the millisecond time scale. It should be pointed out that these residues gave evidence of close contacts with the protein in the complex with the lac operator [Boelens et al. (1987) J. Mol. Biol., 193, 213–216] and that these motions could be implied in the lac-operator-lac-repressor recognition process. 相似文献
13.
Gabriele Schultz Frank Ullrich Knut J. Heller Volkmar Braun 《Molecular & general genetics : MGG》1989,216(2-3):230-238
Summary The FhuA protein in the outer membrane of Escherichia coli serves as a multifunctional receptor for the phages T5, T1, 80, for colicin M, for ferrichrome (Fe3+-siderophore) and for the structurally related antibiotic, albomycin. To determine structural domains required for these receptor functions and for export, a fusion protein between FhuA and Iut (receptor for Fe3+-aerobactin and cloacin DF13) was constructed. In the FhuA-Iut hybrid protein, 24 amino acids of FhuA were replaced by 19 amino acids, 18 of which were from Iut. The number of plaque forming units of phage T5 and T1 on cells expressing FhuA-Iut was nearly as high as on cells expressing plasmid-encoded wild-type FhuA. However, 107-fold higher concentrations of phage 80 and 103 times more colicin M were required to obtain a zone of growth inhibition. Truncated FhuA proteins in which the last 24 amino acids at the carboxy-terminus were replaced by 16 (FhuA2) or 3 (FhuAT) amino acids could hardly be detected on polyacrylamide electrophoretograms of outer membrane proteins, due to proteolytic degradation. Sensitivity of cells expressing FhuA2 to phage T5 and T1 was reduced by several orders of magnitude and sensitivity to phage 80 and colicin M was totally abolished. In contrast, cells expressing FhuAT were nearly as sensitive to phage T5, T1, and 80 and to colicin M as cells containing FhuA-Iut. None of the constructs could grow on ferrichrome as sole iron source and none was sensitive to albomycin. Ferrichrome did not inhibit binding of T5 to TonB– cells expressing FhuA-Iut (as it did in FhuA+ cells) due to the lack of ferrichrome binding. It is concluded that very small deletions (relative to the size of FhuA with 714 amino acids) at the C-terminal end render FhuA susceptible to proteolytic cleavage. The C-terminal alterations affect sensitivity to FhuA-specific agents very differently. Apparently, the C-terminus is a very important part of FhuA regarding stability and activity. Expression of active FhuA and partially inactive FhuA derivatives in the same cell revealed no negative complementation, suggesting a FhuA monomer as functional unit. 相似文献
14.
The production of erythritol and the erythritol yield from glucose by Torula sp. were improved, in increasing order, by supplementing with 10 mg MnSO44H2O l–1, 2 mg CuSO45H2O l–1, and both 10 mg MnSO44H2O l–1 and 2 mg CuSO45H2O l–1. Mn2+ decreased the intracellular concentration of erythritol, whereas Cu2+ increased the activity of erythrose reductase in cells. These results suggest that Mn2+ altered the permeability of cells, whereas Cu2+ increased the activity of erythrose reductase in cells. 相似文献
15.
Rüdiger Bode 《Antonie van Leeuwenhoek》1991,60(2):125-130
The -isopropylmalate (IPM) dehydrogenase (EC 1.1.1.85) ofCandida maltosa, the third pathway-specific enzyme of leucine biosynthesis, was purified, some properties of the enzyme were studied and a novel regulatory pattern was found. The Km values of the enzyme were estimated to be 0.42 mM for -IPM and 0.34 mM for NAD+. It is demonstrated that the enzyme can be regulated by L-valine. The inhibition was competitive with respect to -IPM (Ki=1.84 mM) and non-competitive with respect to NAD+ (Ki=5.67 mM). Exogenous addition of L-valine toC. maltosa cells increased the intracellular pool of some intermediates of leucine biosynthesis (-ketoisovalerate, -IPM, -IPM), but has hardly influence on the leucine pool. 相似文献
16.
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
17.
Jacques B. Baldensperger 《Archives of microbiology》1978,119(3):237-244
Superoxide dismutase has been purified to homogeneity from aerobically grown Thiobacillus denitrificans strain RT. It has a molecular weight of 43,000, is composed of two identical subunits which are not covalently bound, and contains 1.35 atom of iron per molecule. Absorption spectra and amino acid analysis are similar to those of other Fe-superoxide dismutases from bacteria. Aerobically and anaerobically grown cells contain the same Fe-enzyme with similar levels of activity. Manometric sulfite oxidation measurements suggest for the enzyme a protective function of sulfite against the autooxidation initiated by superoxide free radicals.Non-Standard Abbreviations DMSO
dimethyl sulfoxide
- SDS
sodium dodecyl sulfate
- SOD
superoxide dismutase 相似文献
18.
The effects of light and several photosynthetic inhibitors on the rate of sulfite metabolism in cells obtained from Cucumis sativus L. cotyledons was studied. The cells were treated with 200 M Na2SO3 and the disappearance of sulfite was monitored using either dithiobisnitrobenzoic acid or fuchsin. The rate of sulfite disappearance in light was double the dark rate. Disalicylidene propanediamine at 1 mM increased this light-enhanced metabolism approx. 50%; neither 1 M 3,4-dichlorophenyl-N,N-dimethylurea nor 0.1 mM cyanazine, which completely inhibited CO2-dependent oxygen evolution, affected the rate of sulfite metabolism. Addition of 200 M Na2SO3 to the cells partially inhibited 14CO2 fixation. The rate of sulfite consumption by the cells did not affect this inhibition. We conclude that light-dependent sulfite metabolism is cucumber cells may utilize reduced ferredoxin generated as a result of photosynthetic electron transport. An injurious interaction between CO2 fixation and sulfite appears to occur independently of the sulfite-metabolism process.Abbreviations DCMU
3,4-dichlorophenyl-N,N-dimethylurea
- DSPD
disalicylidene propanediamine
- DTNB
5,5-dithiobis-(2-nitrobenzoic acid) 相似文献
19.
The metabolism of GA29 in maturing seeds of Pisum sativum cv. Progress No. 9 was further investigated, and the utility of 2H-labelled GAs in conjuction with GC-MS is illustrated. Using [2-2H1]GA29 as an internal standard, endogenous GA29 was shown to reach a maximal level (ca. 10 g/seed) 27 days from anthesis, and to decline to ca. 1.6 g/seed in mature seeds. In a time-course feed the metabolism of [2-2H1] [2-3H1]GA29 applied to 27 day old seeds, and of endogenous GA29, was compared from the 1H:2H ratios in the recovered GA29. Although both [2-2H1] [2-3H1]GA29 and endogenous GA29 were metabolised to the same limited extent to a putative conjugate, in the main metabolic process endogenous GA29 was preferentially converted to an untraceable (i.e. unlabelled) metabolite. In contrast, endogenous GA29 and [1,3-2H2] [1,3-3H2]GA29, derived from [1,3-2H2] [1,3-3H2]GA20 in a time-course feed, were metabolised in an identical manner. In the latter case isotope loss precluded identification of the metabolite. The structure (8) has been assigned to a GA catabolite present in maturing seeds and seedlings of pea. The isotope data are consistent with this compound being the hitherto untraced metabolite of GA29 in pea.Abbreviations GAn
gibberellin An
- GC
gas chromatography
- GC-MS
combined gas chromatography-mass spectrometry
- GC-RC
combined gas chromatography-radio counting
- M+
molecular ion
- Me
methyl ester
- RT
retention time
- SICM
selected ion current monitoring
- TLC
thin layer chromatography
- TMS
trimethylsilyl ether 相似文献
20.
The trisaccharide 2-(p-trifluoroacetamidophenyl)ethyl 2-acetamido-2-deoxy-4-O-[2-O-(-l-fucopyranosyl)--d-galactopyranosyl]--d-glucopyranoside 1 and the tetrasaccharide 2-(p-trifluoroacetamidophenyl)ethyl 2-acetamido-2-deoxy-3-O-(-l-fucopyranosyl)-4-O-[2-O-(-l-fucopyranosyl)--d-galactopyranosyl]--d-glucopyranoside 2 were synthesized. Thioglycosides, suitably protected, activated directly with methyl trifluoromethanesulfonate or dimethyl(methylthio)sulfonium tetrafluoroborate or activated after bromine treatment with halophilic reagents, were used as glycosyl donors in the construction of the glycosidic linkages.Abbreviations DMTSB
dimethyl(methylthio)sulfonium tetrafluoroborate
- Phth
phthaloyl
- MBn
p-methoxybenzyl
- ClBn
p-chlorobenzyl 相似文献