首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
Measurement of isotope ratios in 1α,2α,3β-trihydroxy-p-menthane, which has been biosynthesized in Fusicoccum amygdali from 3H- and 14C-labelled mevalonate and in its degradation product diosphenol indicates that: (a) four tritium atoms arising from [5-3H2, 2-14C]MVA are retained, one more than suggested from the hydroxylation pattern, (b) menth-2-ene-1-ol is generated from an α-terpinyl cation through a 1,3-hydride shift and (c) trans-cleavage of an α-epoxide by hydrolysis gives 1α,2α,3β-trihydroxy-p-menthane.  相似文献   

2.
Anordrin, an antifertility agent that is an antiestrogen with weak estrogenic activity, has been studied to further characterize its hormonal activities. A dose of 2.0 μg/mouse·day for 7 days did not increase the uterine content of protein, but it did inhibit to a small extent the effect of administered estradiol-17β on uterine protein content and more significantly the effect of estradiol-17β on the uterine content of progesterone receptors. Anordrin also decreased serum corticosteroid-binding globulin levels. Administration of an average daily dose of 160 μg/day of anordrin to intact male mice had no effect on weights of kidney, testis, or seminal vesicle after 10 days, but seminal vesicle weight was significantly decreased after 30 days at a slightly lower dose. Similarly, anordrin inhibited the increase in seminal vesicle weight induced by testosterone propionate treatment of castrated mice. In female mice anordrin failed to maintain deciduomata and blocked the ability of progesterone (2.0 mg/mouse·day) to do so. However, anordrin did not compete with the androgen [3H]R1881 for binding in kidney cytosol or with the progestin [3H]R5020 for uterine receptor sites. Anordrin also did not compete with [3H]corticosterone for binding to serum proteins.  相似文献   

3.
Atlantic bluefin tuna (BFT) (Thunnus thynnus) is of great economic significance for world aquaculture and therefore it is necessary to ensure optimal and sustainable conditions for the farming of this species. Intensive culture of fish may be limited by infectious diseases that can impact on growth performance and cause heavy losses. However, to date there are no reports of cloning and expression analysis of any major immune genes of Atlantic BFT although some immune genes are known in other BFT species. Therefore the aim of this study was to characterize the first cytokine molecules in Atlantic BFT, through: 1) Isolation of full-length cDNA and gene sequences of TNFα1, TNFα2 and IL-1β, 2) comparison of these molecules to known sequences in other vertebrates, especially teleost fish, by multiple sequence alignment, phylogenetic tree analysis and homology modeling; 3) Quantification of in vivo expression of these cytokines in selected tissues in reared BFT over the duration of the farming process. The results indicated that these three cytokines could have value for monitoring Atlantic BFT health status. Curiously, the liver seemed to be an important site of cytokine production during poor health conditions in this species, perhaps reflecting its role as an important organ involved in fish defenses.  相似文献   

4.
Progesterone biotransformation with recombinant yeasts Yarrowia lipolytica E129A15 and Saccharomyces cerevisiae GRF18/YEp5117 expressing bovine adrenocortical cytochrome P-45017 yielded 17-hydroxyprogesterone and two diols, 17,20- and 17,20-dihydroxypregn-4-en-3-ones. The oxidation of mixtures of the three steroids with chromic acid resulted in the cleavage of 17–20 bonds in the diols with the formation of androst-4-ene-3,17-dione. The biotransformation of pregn-4-ene-20-ol-3-one by means of Y. lipolytica E129A15 was accompanied by the following reactions: the primary oxidation of these compounds to progesterone and the subsequent successive reactions of 17-hydroxylation and 20- and 20-reduction. The results widen the possibilities of enzymatic and chemical modifications of steroids.  相似文献   

5.
The neutral urinary excretion products of 17β-hydroxy-2α,3α-cyclopropano-5α-androstane from the rabbit, dosed orally, were investigated. Column chromatography yielded five crystalline metabolites which were identified by GLC and spectroscopic measurements. Three of these substances were hydroxylated in the 4α-position and one in the 6a-position with the cyclopropane ring intact. The fifth substance, 17β-hydroxy-3β-methyl-5α-androstan-2-one, can be derived from initial hydroxylation of the cyclopropane ring at C-2 followed by ring opening. The dosed substance and triol material was shown to be present by GLC and m.s. measurements. GLC determinations show that hydroxylation has occurred at C-4?C-6>C-2.  相似文献   

6.
Incubation of 3α, 20β-hydroxysteroid dehydrogenase (3α, 20β-HSD; E.C.1.1.1.53) with the nucleoside 5'-p-fluorosulfonylbenzoyladenosine (FSA) caused a time-dependent and irreversible loss in enzyme activity. Both 3α- and 20β-hydroxysteroid oxidoreductase activities decreased at equal rates by a first order kinetic process (in 0.05m phosphate buffer at pH 6.0 and 25°C, t12 = 170 min). Incubation of 3α, 20β-HSD was quenched by addition of 2-mercaptoethanol which instantaneously reacts with the fluorosulfonyl group of FSA. The cofactor NADH protected 3α, 20β-HSD against inactivation by FSA, in a concentration-dependent manner. However, progesterone did not protect 3α, 20β-HSD against inactivation by FSA. Evidently, FSA causes inactivation of the enzyme by irreversibly binding to the NADH-binding region at the active site of 3α, 20β-HSD. Both 3α- and 20β-hydroxysteroid oxidoreductase activities disappeared at equal rates under a variety of enzyme-inactivating conditions. These results suggest that both 3α- and 20β-activites occur at the same active site of 3α, 20β-HSD.  相似文献   

7.
The effect of estradiol, hydrocortisone and progesterone on 3,20-and 3,17-hydroxysteroid dehydrogenase (HSD) in mutants of Streptomyces hydrogenans was compared to the steroid response of the wild type. Mutants were defective in arginine biosynthesis and/or aerial mycelial formation and lacked both enzymes or only 17-HSD. Some 17-HSD mutants had lost the ability to be induced by estradiol, by progesterone or by both. Some 20-HSD mutants had lost the ability to be induced by hydrocortisone, by progesterone or by both. Non-inducibility of 17-and 20-HSD by progesterone was not co-ordinate. An additional study of the growth phase-dependent enzyme activity of the wild type after induction with estradiol, hydrocortisone and progesterone was performed.Non-standard abbreviations 17-HSD 3,17-Hydroxysteroid dehydrogenase (EC 1.1.1.51) - 20-HSD 3,20-hydroxysteroid dehydrogenase (EC 1.1.1.53) - AO acridine orange - EBr ethidium bromide - EMS ethyl methanesulfonate - MNNG N-methyl-N-nitro-N-nitrosoguanidine  相似文献   

8.
The diverse biological activities of ??-hydroxyalkenal phospholipids and their involvement in disease are the subject of intense study. Phospholipid aldehydes, such as the 4-hydroxy-7-oxohept-5-enoic acid ester of 2-lyso-phosphatidylcholine (HOHA-PC), the 5-hydroxy-8-oxo-6-octenoic acid ester of 2-lyso-PC (HOOA-PC), and the 9-hydroxy-12-oxododec-10-enoic acid ester of 2-lyso-PC (HODA-PC), are generated by oxidative cleavage of polyunsaturated fatty acyl phospholipids. To facilitate investigations of their chemistry and biology, we now report efficient total synthesis of HOOA, HODA, and HOHA phospholipids. Because the target ??-hydroxyalkenals readily decompose through oxidation of the aldehyde group to a carboxylic acid or through cyclization to furans, these synthesis generate the sensitive functional array of the target phospholipids under mild conditions from acetal derivatives that are suitable for long-term storage.  相似文献   

9.
Datura meteloides; plants were fed with tiglic acid-[-14C] via the roots and after 2 days the percentage incorporation into the alkaloids 3α-tigloyloxytropane, 3α,6β-ditigloyloxytropane, meteloidine and 3α,6β-ditigloyloxytropan-7β-ol were 15·2, 1·82, 2·2 and 1·8 respectively. 3α,6β-Ditigloyloxytropane was partially hydrolysed to 6β-hydroxy-3α-tigloyloxytropane which contained 58·1% of the radioactivity of the original base, whereas 3α,6β-ditigloyloxytropan-7β-ol gave meteloidine containing only 9·2% of the original activity. The results suggest that the di- and tri-hydroxytropanes may be formed by different routes.  相似文献   

10.
11.
Richmond V  Garrido Santos GA  Murray AP  Maier MS 《Steroids》2011,76(10-11):1160-1165
Disodium 2β,3α-dihydroxy-5α-cholestan-6-one disulfate (8) has been synthesized using cholesterol (1) as starting material. Sulfation was performed using trimethylamine-sulfur trioxide complex in dimethylformamide as the sulfating agent. The acetylcholinesterase inhibitory activity of compound 8 was evaluated and compared to that of disodium 2β,3α-dihydroxy-5α-cholestane disulfate (10) and diols 7 and 9. Compounds 8 and 10 were active with IC(50) values of 14.59 and 59.65 μM, respectively. Diols 7 and 9 showed no inhibitory activity (IC(50)>500 μM).  相似文献   

12.
A series of novel 3β, 7α, 11α-trihydroxy-pregn-21-benzylidene-5-en-20-one derivatives were synthesized and characterized by NMR, HRMS. The pregnenolone (1) was first biotransformed by Mucor circinelloides var lusitanicus to 3β, 7α, 11α-trihydroxy-pregn-5-en-20-one (3), then 3 was treated with various benzaldehydes to produce 3β, 7α, 11α-trihydroxy-pregn-21-benzylidene-5-en-20-one derivatives. These derivatives showed remarkable activity against EC109 cells. The absolute configuration of 3 was also confirmed by signal-crystal X-ray analysis.  相似文献   

13.
A single thin layer chromatography and three antibodies were used for the specific radioimmunoassay of four androgens in pooled rat plasma (Sprague-Dawley adult males). The following values were found (pg/ml ± SD). Testosterone : 3, 138 ± 173; dihydrotestosterone : 374 ± 20; 5α-androstane-3α 17β-diol : 284 ± 24; 5α-androstane-3β, 17β-diol : 223 ± 11.  相似文献   

14.
15.
We determined the substrate specificities of the protein tyrosine phosphatases (PTPs) PTP1B, RPTPα, SHP-1, and SHP-2 by on-bead screening of combinatorial peptide libraries and solution-phase kinetic analysis of individually synthesized phosphotyrosyl (pY) peptides. These PTPs exhibit different levels of sequence specificity and catalytic efficiency. The catalytic domain of RPTPα has very weak sequence specificity and is approximately 2 orders of magnitude less active than the other three PTPs. The PTP1B catalytic domain has modest preference for acidic residues on both sides of pY, is highly active toward multiply phosphorylated peptides, but disfavors basic residues at any position, a Gly at the pY-1 position, or a Pro at the pY+1 position. By contrast, SHP-1 and SHP-2 share similar but much narrower substrate specificities, with a strong preference for acidic and aromatic hydrophobic amino acids on both sides of the pY residue. An efficient SHP-1/2 substrate generally contains two or more acidic residues on the N-terminal side and one or more acidic residues on the C-terminal side of pY but no basic residues. Subtle differences exist between SHP-1 and SHP-2 in that SHP-1 has a stronger preference for acidic residues at the pY-1 and pY+1 positions and the two SHPs prefer acidic residues at different positions N-terminal to pY. A survey of the known protein substrates of PTP1B, SHP-1, and SHP-2 shows an excellent agreement between the in vivo dephosphorylation pattern and the in vitro specificity profiles derived from library screening. These results suggest that different PTPs have distinct sequence specificity profiles and the intrinsic activity/specificity of the PTP domain is an important determinant of the enzyme's in vivo substrate specificity.  相似文献   

16.
5α-Androstane-3α, 16α 17β-triol was synthesized from 3β-hy-droxy-5-androsten-17-one. The procedure Involved catalytic hydrogenation of 3β-hydroxy-5-androsten-17-one to 3β-hydroxy-5α-androstan-17-one. This was followed by conversion of the 3β-hydroxy group to 3α-benzoyloxy group by the Mitsunobu reaction. Further treatment with isopropenyl acetate yielded 5α-androsten-16-ene-3α, 17-diol 3-benzoate 17-acetate. This was then converted to 3α, 17-dihydroxy-5α-androstan-16-one 3-benzoate 17-acetate via the unstable epoxide intermediate after treatment with m-cloroperoxybenzoic acid. LiAlH4 reduction of this compound formed 5α-androstane-3α, 16α, 17β-trlol. 1H and 13C NMR of various steroids are presented to confirm the structure of this compound.  相似文献   

17.
The metabolic fate of the bile add analogs, 3α,7α-dihydroxy-7β-methyl-5β-cholanoic acid and 3α,7β-dihydroxy-7α-methyl-5β-cholanoic acid, was investigated and compared with that of chenodeoxycholic acid in hamsters. Both bile acid analogs were absorbed rapidly from the intestine and excreted into bile at similar to that of chenodeoxycholic acid. In the strain of hamster studied, the biliary bile were conjugated with both glycine and taurine. After continuous intravenous infusion, chenodeoxycholic acid the analogs became the major bile acid constituents in bile. After oral administration of a single dose of these compounds, fecal analysis revealed the existence of unchanged material (25–35%) as well as considerable amounts of metabolites (65–75%). The major metabolites excreted into feces were more polar than the starting material and were tentatively identified as trifaydroxy-7-methyl compounds by radioactive thin-layer chromatography. However, monohydroxy compounds were also found in the fecal extracts. These results show that chenodeoxycholic acid and ursodeoxycholic acid with a methyl group at the 7-position are resistant to bacterial 7-dehydroxylation than the normally occurring bile acids and that a certain proportion of these analogs is hydroxylated to give the corespondiag trihydroxy compound(s), In a control experiment, about 5% of administered chenodeoxychoulic acid was metabolized to a trihydroxy feile acid, but most of the compound (95%) was transformed into lithocholic acid.  相似文献   

18.
Both the 5α, 6α- and 5β, 6β-dichloromethylene adducts (2a and 2b) of 3β-acetoxy-5-androsten-17-one (1) are produced when the latter is exposed to dichlorocarbene generated from chloroform and base by Phase Transfer Catalysis using ultrasound as a means of agitation. The 1H NMR substituent effects of 5α, 6α- and 5β, 6β-dichloromethylene on the angular methyl groups (Zürcher values) are given. The 13C NMR spectra for both compounds are presented and discussed.  相似文献   

19.
Cellulose production by Acetobacter strains is enhanced by the addition of a small amount of cellulose to the production culture. The effect of an endo-β-1, 4-glucanase from Bacillus subtilis on the cellulose production by Acebohacter xylinum BPR2001 was examined by adding various amounts of the purified glucanase to the culture. The addition of a small amount of this glucanase enhanced cellulose production. Furthermore, it reduced the amount of a polysaccharide called acetan produced. However, an active-site mutant enzyme of the glucanase, which showed no enzyme activity but still had cellulose-binding ability, had no effect on cellulose production. It was concluded, therefore, that the endoglucanase activity itself, but not the cellulose-binding ability, was essential for the enhancement of cellulose production. The structural properties of the cellulose produced in the presence of the endoglucanase were found to be almost identical to those of native bacterial cellulose.  相似文献   

20.
We have applied and validated a recently described method (real-time quantitative PCR) for cytokine mRNA quantification. This method is easy to optimise and offers sensitive, reliable and quantitative results with significantly reduced labour, allowing the simultaneous analysis of cytokine expression for large numbers of samples. With this method the expression levels of several cytokines (TNF- and TGF-1) and their receptors (FAS, TNFR1 and 2) have been compared between eosinophilic and neutrophilic granulocytes isolated from peripheral blood. No differences were found using the healthy volunteer samples.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号