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1.
The in vitro reaction of bacteriophage T7-DNA with the radioactive diastereomeric benzo(a)pyrene-diol-epoxides, (±) [3H9, 3H10]-7β,8α-dihydroxy-9α,10β-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene, and (±) [3H9, 3H10]-7β,8α-dihydroxy-9β,19β-epoxy-7,8,9,10-tetrahydrobenzo(1)pyrene, was investigated. Chromatographic analysis of digests of the DNA allowed the distinction of characteristic deoxynucleoside adduct peaks for the two benzo(a)pyrene-diol-epoxides. Our results, together with data from the literature, allow the identification of these adducts as mostly N2-(10-7β,8α,9α-trihydroxy-7,8,9,10-tetrahydrobenzo(a)pyreney1)deoxyguanosine and N2-(10-7β,8α,9β-trihydroxy-7,8,9,10-tetrahydrobenzo(a)pyreney1)deoxyguanosine, respectively. DNA-benzo(a)pyrene adducts with the same chromatographic properties were formed in mouse embryo fibroblasts upon treatment with benzo(a)pyrene.  相似文献   

2.
α-Cyanoglycine inactivates the pyridoxal-P forms of the β2 subunit and the α2β2 complex of tryptophan synthase; an intense chromophore at 430 nm forms concomitantly. The slow reactivation of the modified β2 subunit upon dialysis (t12 = 24 hours) is prevented by addition of α subunit, which presumably acts by changing the environment of the chromophoric derivative. These data and the observed protection from inhibition by L-serine indicate that α-cyanoglycine acts as a substrate analog which undergoes a second, largely irreversible reaction at the active site of the β2 subunit. Modification of the β2 subunit increases its affinity for the α subunit. Modification of the α2β2 complex increases its stability to heat, urea, and low pH.  相似文献   

3.
A new polyhydroxysterol 1β,3β,5,6β-tetrahydroxy-5α-androstan-17-one (1) was isolated from the soft coral Sarcophyton glaucum. The structure of 1 was deduced from comparison of the spectral data with those of known 1β,3β,5α,6β-tetrahydroxysterols and confirmed by the synthesis starting from 1β,3β-dihydroxy-5,16-pregnadien-20-one (6a)  相似文献   

4.
A series of 12α-hydroxy steroids with varying side chains was prepared, and their 24-hour acetylation yields were compared, l2α-Hydroxy-5β-pregnan-20-one (lb) was prepared from 3α, 12α-diacetoxy-5β~pregnan-20-one (2) and also by side chain degradation of 12α-acetoxy-5β-cholanoic acid (5d). 21-Benzyl-5β-pregnan-12α-ol (1g) was synthesized by hydrogenation of the 21-benzylidine derivative of ketone 1b. 23-Pheny1-5β-norcholan-12α-ol (1k) was obtained by the Grignard reaction of 2-phenyl-ethylmagnesium bromide and ketone 1b, dehydration, hydrogenation and hydride reduction; a similar sequence produced 20-methyl-5β-pregnan-12α-ol (lm). The acetylation results (Table 11) imply that branching at C-20 may be more significant for 12α-hydroxyl reactivity than side chain length or type. An additional compound with an unbranched side chain, 21-nor-5β-cholan-12α-ol (14), was synthesized by a Grignard reaction on the 21-bromo intermediate 11b. Acetylation rates determined by glc indicate (Table 111) That compounds with unbranched side chains have 12α-hydroxyl groups about ten times as reactive as their analogs with 20-methyl groups.  相似文献   

5.
Inactivation of Q beta RNA by electrophiles   总被引:1,自引:0,他引:1  
Methyl, ethyl and isopropyl methanesulfonates (MMS, EMS, iPMS), diethyl pyrocarbonate (DEP) and autoclaved irradiated sucrose and glucose (active principles presumably α,β-unsaturated carbonyl compounds) inactivated the transfectivity of Qβ RNA in one-hit processes. In the case of DEP, nealy every carbethoxy group introduced inactivated, whereas several alkyls from the methanesulfonates per RNA molecule seemed te be tolerated. 1,2-Dibromoethane was a relatively strong inhibitor of RNA transfectivity in the presence of thioglycol, probably via the formation of a more reactive “half mustard”.Compared with isolated RNA, the complete Qβ phage was somewhat protected against methanesulfonates but slightly more sensitive to the irradiated sugars and distinctly more sensitive to DEP, indicating that the two latter compounds may inactivate in reactions with coat proteins.The negative tests with the strongly mutagenic 2,3,7,8-tetrachlorodibenzdioxin suggest that intercalating agents are probably not active towards RNA.The decrease of the trasnfectivity of Qβ RNA may be used as a sensitive system to determine reactivity towards nucleic acids of environmental pollutants.  相似文献   

6.
The syntheses of (±) 2α,6β-diethyl-7α-ethynyl-3α-(p-hydroxyphenyl)-trans-bicyclo[4.3.0]nonan-7β-ol (8), (±)2β,6β-diethyl-7α-ethynyl-3β-(p-methoxyphenyl)-trans-bicyclo[4.3.0]nonan-7β-ol (12) and (±) 2α,6β-diethyl-7α-ethynyl-3β-(p-hydroxyphenyl)-trans-bicyclo[4.3.0]nonan-7β-ol (18) and their derivatives, which are essentially B-seco-steroids having cis-anti-trans, cis-syn-trans and trans-anti-trans geometries have been carried out. A study of their antiimplantation activities (AI) and receptor binding affinities (RBA) show that trans-anti-trans compounds are biologically most potent, followed by the corresponding cis-anti-trans and cis-syn-trans compounds. The most potent compound 18 is active at 1 mg/kg in rats. Introduction of 7α-ethynyl group increases their AI activity; however, no significant effect on their RBA is observed.  相似文献   

7.
L S Graham  L R Bennett 《Steroids》1974,23(3):311-321
Capsules prepared from polydimethylsiloxane (PDS) tubing and containing tritium labeled 11β, 17α, 21-trihydroxy-4-pregnene-3, 20-dione (cortisol) were implanted subcutaneously in six mongrel dogs. Invivo diffusion rates were found to decline at a single exponential rate after a period of rapid, initial change. Diffusion of the steroid from the capsule provided an exogenous marker which can be used for the continuous monitoring of metabolic clearance rates and production rates in the normal state and during metabolic insults. Comparison of the temporal aspects of plasma radioactive concentration and excretion of radioactivity suggests the existence of a tightly bound plasma component serving as a reservoir of cortisol.  相似文献   

8.
M Kobayashi  H Mitsuhashi 《Steroids》1974,24(3):399-410
Occelasterol, a new marine C27 sterol, has been isolated from an annelida, Pseudopotamilla occelata and its structure was confirmed as 22-trans-27-nor-(24S)-24-methylcholesta-5, 22-dien-3β-ol (IIa) from the spectral data and by synthesis. Thissterol, the second member of a class of sterols having 27-norergostane-type side chain, had been formerly regarded as 22-cis-cholesta-5, 22-dien-3β-ol (Va). Gas-liquid Chromatographic studies have shown that occelasterol is distributed in various amounts in most of marine invertebrates.  相似文献   

9.
A novel synthesis of 16α-hydroxy-4-androstene-3,17-dione (3), 16α-hydroxy-4-androstene-3, 6,17-trione (4), 17β-amino-5-androsten-3β-ol (10) and 17β-amino-4-androsten-3-one (14) is described. 16α-Bromoacetoxy-4-androstene-3, 17-dione (5), 16α-bromoacetoxy-4-androstene-3, 6,17-trione (6) and 17β-bromoacetylamino-4-androsten-3-one (15) were synthesized as potentially selective irreversible inhibitors of androgen aromatases. 16α-Bromo-4-androstene-3,17-dione (1) and 16α-bromo-4-androstene-3, 6,17-trione (2) were converted to compounds 3 and 4 in 80–90% yield by controlled stereospecific hydrolysis using sodium hydroxide in aqueous pyridine. Reductive amination of 3β-hydroxy-5-androsten-17-one and 3-methoxy-3,5-androstadien-17-one (11) using ammonium acetate and sodium cyanohydridoborate (NaBH3CN) and a subsequent treatment with acid gave the amines 10 and 14 respectively, as a salt. The corresponding 17-imino compounds 9 and 13 were also isolated from the reaction mixtures when methanol was used as a solvent for the reaction. The 16α-hydroxyl compounds 3 and 4 and the 17β-amino compound 14 were con- verted to the corresponding bromoacetyl derivatives, 5, 6, and 15, with bromoacetic acid and N,N'-dicyclohexylcarbodiimide.  相似文献   

10.
The epididymis of adult rats metabolize 3H-testosterone by experiments in vivo. Thirty minutes after the injection of 100 μCi 3H-testosterone, some 10 per cent of the total radioactivity of the epididymis was found in the water-soluble fraction, whereas 90 per cent was found in the ether soluble fraction (free steroids). The free steroids were examined further and the following androgenic metabolites identified: testosterone (17β-hydroxy-4-androsten-3-one) 8, 9%, androstendipne (4-androstene-3, 17-dione, 2,7%,5α-A-dione (5α-androstane-3, 17-dione) 6,5%, DHT (17β-hydroxy-5α-androstan-3-one) 47, 2%, 3β-diol (5α-androstane-3β, 17β-diol) 4, 4%, 3α-diol (5α-androstane-3α,17β-diol) 20, 8% and androsterone (3α-hydroxy-5α-androstan-3-one) 3,4%. The relative amount of each metabolite is given in per cent of total radioactivity in the ether soluble fraction.  相似文献   

11.
A formal synthesis of dl-18-hydroxyestrone has been achieved by the preparation of dl-3-methanesulfonyloxy-13β,17β-dicarboxy-18--norestra-1,3,5(10)-triene anhydride, the dextrorotatory enantiomer of which is an intermediate in Barton's conversion of d-estrone to d-1β-hydroxyestrone (KC-6A).  相似文献   

12.
4β,5-Epoxy-5β-androstane-3,17-dione (1a), 17β-hydroxy-4β,5-epoxy-5β-androstan-3-one (1b) and 17β-acetoxy-4β,5-epoxy-5β-androstan-3-one (1c) were treated with anhydrous hydrogen fluoride in pyridine (70% solution) at 55° and yielded the corresponding 4-en-4-ols e.g. 4-hydroxy-4-androstene-3, 17-dione (2a).As the reaction temperature was lowered each epoxide formed a second product which, at ?75°, was the major component of the reaction mixture and was identified as the 5α-fluoro-4α-ol derivative of the parent enone, e.g. 4α-hydroxy-5-fluoro-5α-androstane-3,17-dione (3a). These fluorohydrins are thermally unstable, losing hydrogen fluoride.The acetates of the fluorohydrins were also prepared, characterized, and shown to be more stable than the parent alcohols.  相似文献   

13.
The administration of preferential adrenergic receptor antagonists to uninephrectomized rats revealed the β2-adrenergic mediation in diamine oxidase activity increase that occurs in the remaining kidney undergoing compensatory hypertrophy. In fact, β12- or β2-, but not α1-, α2-, or β1-receptor-blocking this enzyme enhancement. Further studies with adrenoceptor agonists, such as epinephrine (α1, α2, β1, β2), isoproterenol (β1, β2) or terbutaline (β2) showed that also in normal rat kidney diamine oxidase activity is under the control of catecholamine2-receptors through a mechanism that involves new synthesis of mRNA and protein. Theophylline, an inhibitor of phosphodiesterase, or forskolin, an activator of adenyl cyclase, increased diamine oxidase activity as does epinephrine or nephrectomy. Thus, catecholamine-triggered β2-receptors coupled to adenyl cyclase are involved in the regulation of diamine oxidase activity in normal and hypertrophic rat kidney.  相似文献   

14.
The presence of 5β-cholanic acid has been detected in the seeds of jequirity bean (Abrusprecatorius L.) Its structure was unequivocally established by spectroscopic methods. This report provides proof, for the first time, of the occurrence of 5β-cholanic acid in a plant source.  相似文献   

15.
Neurobiology of tetrahydro-beta-carbolines   总被引:1,自引:0,他引:1  
N S Buckholtz 《Life sciences》1980,27(11):893-903
Tetrahydro-β-carbolines (THβC's) are tricyclic compounds structurally related to the indoleamines. Recent studies have reported the invitro and invivo formation of these compounds in brain and other tissues. This information and other data indicating that THβC's interact relatively specifically with various aspects of the serotonergic neurotransmitter system has suggested that THβC's may serve as endogenous neuromodulators of neurotransmitters. Evidence for the formation of these compounds as well as their neurochemical, neuroendocrinological, and behavioral effects is described in this review.  相似文献   

16.
As part of a program to synthesize the ceramide trisaccharide (1) related to Fabry's disease, methyl 4-O-(4-O-α-d-galactopyranosyl-β-d-galactopyranosyl)-β-d-glucopyranoside (12) was prepared. Methyl β-lactoside (2) was converted into methyl 4-O-(4,6-O-benzylidene-β-d-galactopyranosyl)-β-d-glucopyranoside (4). Methyl 2,3,6-tri-O-benzoyl-4-O-(2,3,6-tri-O-benzoyl-β-d-galactopyranosyl)-β-d-glucopyranoside (7) was synthesized from 4 through the intermediates methyl 2,3,6-tri-O-benzoyl-4-O-(4,6-O-benzylidene-2,3-di-O-benzoyl-β-d-galactopyranosyl)-β-d-glucopyranoside (5) and methyl 2,3,6-tri-O-benzoyl-4-O-(2,3-di-O-benzoyl-β-d-galactopyranosyl)-β-d-glucopyranoside (6). The halide-catalyzed condensation of 7 with 2,3,4,6-tetra-O-benzyl-d-galactopyranosyl bromide (8) gave methyl 2,3,6-tri-O-benzoyl-4-O-[2,3,6-tri-O-benzoyl-4-O-(2,3,4,6-tetra-O-benzyl-α-d-galactopyranosyl)- β-d-galactopyranosyl]-β-d-glucopyranoside (10). Stepwise deprotection of 10 led to 12, the methyl β-glycoside of the trisaccharide related to Fabry's disease.  相似文献   

17.
The synthesis of 4-ethenylidene-5α-androstane-3β, 17β-diol (5) and of 4-ethenylidene-5α-androstane-3,17-dione (4) is described. Compound 5 is a competitive inhibitor of solubilized bovine microsomal adrenal Δ5-3β-hydroxysteroid dehydrogenase, with Ki =2.7μM, and is converted by the enzyme to the corresponding 3-ketone. Compound 4 shown to irreversibly inactivate the enzyme in a time-dependent manner (t12 =31 min; 55μM; pH =7.0). The substrate, dehydroepiandrosterone, protects against inactivation by compound 4. In contrast, compound 5 is not oxidized at the 3-position by the 3β-(and 17β)-hydroxysteroid dehydrogenase from P. testosteroni, but is oxidized at the 17-position. Nevertheless, the 4-ethenylidene-3,17-diketone (4) causes irreversible time-dependent inactivation (t12 =28min; 64μM; pH =7.0) when incubated directly with this bacterial enzyme, acting as an affinity label.  相似文献   

18.
Thirteen adult and one newborn heterozygotes, and three homozygotes for hemoglobin Constant Spring were examined for globin chain synthesis. Reticulocytes from venous blood were incorporated with [3H]-leucine in an incubation mixture for 3 hours. Globin prepared from the radioactive, washed red cells was fractionated by CM-cellulose chromatography in 8 M urea and the total radioactivity of each globin chain was determined. The mean of αβ ratio in the heterozygotes was 1.34 ± SD 0.08, which is significantly different from that of 1.07 ± SD 0.03 in eleven normal controls. The αβ+γ ratio in the heterozygous neonate was also 1.39. The αβ ratios in the three homozygotes were around 1.6. The α-Constant Spring chain appears to be over produced, but it may be unstable or labile, not fully available for conjugation with the non alpha chains.  相似文献   

19.
This paper describes the synthesis of a series of new 10β-substituted 4-estrene-3,17-dione analogs (1–8). These compounds, together with a number of known analogs (9–14), have been evaluated as reversible or irreversible inhibitors of human placental microsomal aromatase. The best reversible inhibitor is the 10β-vinyl compound (9). The only compounds causing irreversible inhibition of aromatase are the 10β-propargyl compound (1) and the 10β-difluoromethyl compound (12).  相似文献   

20.
Partial invitro sialylation of biantennary and triantennary glycopeptides of α1-acid glycoprotein using colostrum β-galactosideα(2→6) sialyltransferase followed by high resolution 1H-NMR spectroscopic analysis of the isolated products enabled the assignment of the Galβ(1→4)GlcNAcβ(1→2)Manα(1→3)Man branch as the most preferred substrate site for sialic acid attachment. The Galβ(1→4)GlcNAcβ(1→2)Manα(1→6)Man branch appeared to be much less preferred and the Galβ(1→4)GlcNAcβ(1→4)Manα(1→3)Man sequence of triantennary structures was of intermediate preference for the sialyltransferase. The specificity of the β-galactoside α(2→6) sialyltransferase is thus shown to extend to structural features beyond the terminal N-acetyllactosamine units on the oligosaccharide chains of serum glycoproteins.  相似文献   

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