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Biomedical subjects

B Tamaoki

Publications and source records attributed to B Tamaoki.

At least 37 records · Page 2Linked to original sources
PubMed1986

Purification and properties of testicular 3 beta-hydroxy-5-ene-steroid dehydrogenase and 5-ene-4-ene isomerase.

Through the treatment of rat testicular microsomes with sodium cholate, 3 beta-hydroxy-5-ene-steroid dehydrogenase and 5-ene-4-ene isomerase (abbreviated as the 3 beta-hydroxysteroid dehydrogenase and isomerase, respectively) were solubilized, and then purified by DEAE and hydroxylapatite column chromatographies. The findings were as follows: With this purification procedure, the 3 beta-hydroxysteroid dehydrogenase activity could not be separated from the isomerase. For 3-oxo-4-ene-steroid formation from 3 beta-hydroxy-5-ene-steroids, NAD+ was required as a cofactor. While the 3 beta-hydroxysteroid dehydrogenase required NAD+, the isomerase also required NAD+ or its reduced form, in contrast to the microbial enzyme. On treatment of the purified enzyme with 5'-p-fluorosulfonyl-benzoyladenosine (FSBA), both enzyme activities were markedly reduced. The enzyme, affinity labeled with [adenine-8-14C]FSBA, showed a mol. wt of 46.8 K. During 4-androstenedione production from DHA, 5-androstenedione was detected as an intermediate.

3-Hydroxysteroid Dehydrogenases↗
PubMed1986

Reduced activity of androgen biosynthesis in the testes of rats with analbuminemia.

Steroid metabolism in Nagase Analbuminemia Rats (NAR), a mutant strain established from Sprague-Dawley rats, was studied. NAR are characterized by lack of serum albumin and hyperlipidemia. Total testosterone concentration in the serum of NAR was lower than that of normal rats, while the serum free testosterone, LH and FSH concentrations were similar. The half lives of 14C-labeled testosterone administered intravenously in NAR and normal Sprague-Dawley (SD) rats were 4.4 and 4.1 min, respectively. The plasma clearance rates of testosterone in NAR and normal rats were 34.7 and 39.1 ml/min per kg body weight. On Sephadex G-100 chromatography, a mixture of [3H]testosterone and normal rat serum gave two protein peaks eluted in the void volume and the albumin fraction, and the radioactivity was eluted all in the albumin fraction. In contrast, a mixture of [3H]testosterone and NAR serum gave a single protein peak eluted in the void volume and the radioactivity was mainly eluted with this protein peak. The association constants of testosterone to NAR and normal rat sera were 1.25 and 2.24 X 10(4) M-1. Enzyme activities related to the synthesis of testosterone by the testicular microsomal fractions of NAR and normal rats were examined. The activities of 3 beta-hydroxysteroid dehydrogenase, 5-ene-4-ene isomerase, 17 alpha-hydroxylase, C-17-C-20 lyase and 17 beta-hydroxysteroid dehydrogenase were lower in NAR than in normal rats. The activity for synthesis of testosterone from pregnenolone by the testicular microsomal fraction of NAR was about 40% of that of normal rats. These findings indicate that the low serum concentration of testosterone in NAR is mainly attributable to decreased biosynthesis of testosterone in the testes.

Androgens↗
PubMed1985

Effect of Fe2+ -induced lipid peroxidation upon microsomal steroidogenic enzyme activities of porcine adrenal cortex.

When porcine adrenocortical microsomes were treated with Fe2+, enhanced production of malondialdehyde was observed as a result of membrane lipid peroxidation. By treatment of the microsomes with Fe2+, the activity of delta 5-3 beta-hydroxysteroid dehydrogenase coupled with delta 5-delta 4 isomerase, concentration of cytochrome P-450 and the activity of the cytochrome-involving enzyme systems such as 17 alpha- and 21-hydroxylases were significantly reduced. 17 alpha-Hydroxylase activity was more effectively decreased by Fe2+ than that of 21-hydroxylase. On the other hand, activity of NADH- and NADPH-cytochrome c reductases remained unchanged or somewhat increased. Both the induction of lipid peroxidation and the decrease of the enzyme activities were prevented by alpha-tocopherol and N,N' -diphenyl-rho-phenylenediamine.

3-Hydroxysteroid Dehydrogenases↗
PubMed1985

Relationship between the structures and steroidogenic functions of the testes of the urohaze-goby (Glossogobius olivaceus).

The testis of the brackishwater goby (Glossogobius olivaceus, the urohaze-goby in this text) consists of two main components, the glandular and the seminiferous tissue. After manual separation of the two tissues, in vitro steroidogenesis in each tissue was examined using testes from mature males in the breeding season. Cell-free homogenates (800g supernatant fluid) of each tissue were aerobically incubated with 14C-labeled pregnenolone, progesterone, 17 alpha-hydroxyprogesterone, androstenedione, dehydroepiandrosterone, testosterone, or 5 alpha-pregnane-3,20-dione in the presence of NAD+ or NADPH. (1) Glandular tissue: Pregnenolone and dehydroepiandrosterone were converted to progesterone and androstenedione, respectively, in the presence of NAD+. In the presence of NADPH, the following metabolism of steroids was established. Progesterone was transformed to 5 alpha-pregnane-3,20-dione (main product), 17 alpha-hydroxyprogesterone, 17 alpha-hydroxy-5 alpha-pregnane-3,20-dione, and androstenedione. 17 alpha-Hydroxyprogesterone was metabolized into 17 alpha-hydroxy-5 alpha-pregnane-3,20-dione (main product), 3 beta, 17 alpha-dihydroxy-5 alpha-pregnan-20-one, androstenedione, and 5 alpha-androstane-3,17-dione. From androstenedione, 5 alpha-androstane-3,17-dione (main product) and epiandrosterone were obtained. Testosterone was transformed to 5 alpha-dihydrotestosterone (main product), 5 alpha-androstane-3 beta, 17 beta-diol, epiandrosterone, and 5 alpha-androstane-3,17-dione. 5 alpha-Pregnane-3,20-dione was metabolized into 17 alpha-hydroxy-5 alpha-pregnane-3,20-dione, 5 alpha-androstane-3,17-dione, epiandrosterone, and 5 alpha-dihydrotestosterone. (2) Seminiferous tissue: Almost all of the above metabolites were obtained, but the yield was much smaller, especially for 5 alpha-reduced metabolites, compared with that for glandular tissue. From these results, it is concluded that steroidogenesis in the testis of G. olivaceus is characterized by the predominant activity of 5 alpha-reductase and 3 beta-hydroxysteroid dehydrogenase and that these are localized mainly in glandular tissue, together with delta 5-3 beta-hydroxysteroid dehydrogenase + delta 5-delta 4 isomerase, 17 alpha-hydroxylase, and C-17-C-20 lyase.

17-alpha-Hydroxyprogesterone↗
PubMed1985

Affinity labeling of the cofactor-binding site of estradiol 17 beta-dehydrogenase of human placenta by 5'-p-fluorosulfonylbenzoyl adenosine.

An analogue of adenosine nucleotide, 5'-p-fluorosulfonylbenzoyl adenosine (5'-FSB-Ado), appears to interact irreversibly with the cofactor-binding site of estradiol 17 beta-dehydrogenase of human placenta. This conclusion is based on the following observations: (1) The estradiol 17 beta-dehydrogenase is inhibited by 5'-FSB-Ado. When NAD+ is the variable component in the presence of saturated amount of steroid, the type of the inhibition is competitive in nature. When the steroid is the variable component, mode of the inhibition becomes non-competitive. The results suggest reversible binding of 5'-FSB-Ado to the cofactor-binding site of the dehydrogenase. (2) 5'-FSB-Ado inactivates irreversibly the estradiol 17 beta-dehydrogenase in time- and concentration-dependent manners, following pseudo-first-order kinetics. But, no inactivation is observed in the presence of p-fluorosulfonylbenzoic acid, suggesting that adenosine moiety of 5'-FSB-Ado is essential for the affinity labeling of estradiol 17 beta-dehydrogenase. (3) NADP+ protects completely estradiol 17 beta-dehydrogenase from the inactivation of 5'-FSB-Ado, whereas NAD(H) is partially protective against the inactivation, suggesting that phosphate moiety at 2'-position of NADP+ disturbs the covalent binding of 5'-FSB-Ado at or near the cofactor-binding site of the enzyme. (4) 2',5'-ADP shows the significant protection against the inactivation by 5'-FSB-Ado, but less effect is observed in the presence of nicotinamide mononucleotides. These results suggest that 5'-FSB-Ado is an affinity ligand for binding-site of adenosine nucleotide moiety of the cofactor.

17-Hydroxysteroid Dehydrogenases↗
PubMed1985

The presence of essential carboxyl group for binding of cytochrome c in rat hepatic NADPH-cytochrome P-450 reductase by the reaction with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide.

NADPH-cytochrome P-450 reductase (EC 1.6.2.4) purified from rat hepatic microsomal fraction was inactivated by 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC), a specific agent for modification of carboxyl groups in a protein. The inactivation exhibited pseudo-first order kinetics with a reaction order approximately one and a second-order-rate constant of 0.60 M-1 min-1 in a high ionic strength buffer and 0.08 M-1 min-1 in a low ionic strength buffer. By treatment of NADPH-cytochrome P-450 reductase with EDC, the pI value changed to 6.5 from 5.0 for the native enzyme, and the reductase activity for cytochrome c, proteinic substrate, was strongly inactivated. When an inorganic substrate, K3Fe(CN)6, was used for assay of the enzyme activity, however, no significant inactivation by EDC was observed. The rate of inactivation by EDC was markedly but not completely decreased by NADPH. Also, the inactivation was completely prevented by cytochrome c, but not by K3Fe(CN)6 or NADH. The sulfhydryl-blocked enzyme prepared by treatment with 5,5'-dithio-bis(2-nitrobenzoic acid), which had no activity, completely recovered its activity in the presence of dithiothreitol. When the sulfhydryl-blocked enzyme was modified by EDC, the enzyme in which the carboxyl group alone was modified was isolated, and its activity was 35% of the control after treatment with dithiothreitol. In addition, another carboxyl reagent, N-ethyl-5-phenylisoxazolium-3'-sulfonate (Woodward reagent K), decreased cytochrome c reductase activity of NADPH-cytochrome P-450 reductase. These results suggest that the carboxyl group of NADPH-cytochrome P-450 reductase from rat liver is located at or near active-site and plays a role in binding of cytochrome c.

Animals↗
PubMed1984

The reaction of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide with an essential carboxy group of human placental estradiol 17 beta-dehydrogenase.

Estradiol 17 beta-dehydrogenase from human placenta was inactivated by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC), a specific reagent for modification of carboxyl group in a protein. Inactivation of the dehydrogenase by EDC progressed in time-dependent, concentration-dependent and ionic strength-dependent manners. In the presence of NAD+ or NADP+, the inactivation rate by EDC was markedly accelerated. NMN+ and acetylpyridine-DPN+ also appeared to increase the rate of modification of the dehydrogenase by EDC, but no acceleration of the inactivation was observed in the presence of the reduced forms of those nucleotides. Inactivation by EDC in the presence of NAD+ was accompanied by incorporation of 2 mol of NAD+/mol of dimer (Mr = 68,000) of the enzyme. When the dehydrogenase was incubated with EDC together with estriol, the activity was lost slower than that of control without the steroid. Similarly, the inactivation was prevented by addition of estrone and estradiol as well as aminoestrogens. From those results, we suggest that the carboxyl group essential for the function of estradiol 17 beta-dehydrogenase is buried in the enzyme molecule, and the positive charge of nicotinamide N1 of the oxidized form of the cofactor plays an important role for enhancement of the inactivation by EDC.

17-Hydroxysteroid Dehydrogenases↗
PubMed1984

In vivo estradiol production in postovulatory ovaries is enhanced by administration of testosterone but not by 5 alpha-dihydrotestosterone.

Pre- and postovulatory states of ovaries were induced by the injection of PMSG and PMSG + hCG treatments, respectively, to immature rats. The concentration of ovarian estradiol measured by radioimmunoassay decreased significantly following hCG treatment to PMSG-pretreated rats. Subcutaneous administration of testosterone in soybean oil-glycerol mixture (9:1, v/v) restored the decreased concentration of the ovarian estradiol markedly in the PMSG + hCG treated rats, but not in the group treated with PMSG alone or in the control group treated with no gonadotropin. On the other hand, 5 alpha-dihydrotestosterone showed no increase in the ovarian estradiol of any group. When an ethanol solution of testosterone was administered s.c. to the PMSG + hCG treated rats, the ovarian estradiol level was maximally enhanced from 0.5 to 1.0 h after the injection. On the other hand, 5 alpha-dihydrotestosterone, dehydroepiandrosterone and 17 alpha-hydroxyprogesterone in ethanol showed no effect 1 h after the injection. These results indicate that the drastic decrease in ovarian estradiol production due to the hCG administration is caused by an acute decrease in the supply of aromatizable androgens to ovarian aromatase.

Animals↗
PubMed1984

Contribution of cytochrome b5 to androgen synthesis in rat testicular microsomes.

Cytochrome b5 was purified from porcine testicular microsomes, and its amino acid composition was determined. Rabbit antibody against the purified cytochrome b5 was prepared in order to study the contribution of cytochrome b5 to testicular microsomal oxygenases related to androgen production. In the presence of NADPH alone as the electron donor, the antibody against cytochrome b5 inhibited the activities of steroid 17 alpha-hydroxylase and C-17-C-20 lyase of rat testicular microsomal fraction. Addition of NADH to the NADPH-supported oxygenase assay system enhanced both steroid oxygenase activities, and addition of the antibody against cytochrome b5 decreased the NADH-caused stimulation of steroid 17 alpha-hydroxylase and C-17-C-20 lyase activities. When dehydroepiandrosterone and NAD+ were added as substrates for 3 beta-hydroxy-delta 5-steroid dehydrogenase in order to synthesize NADH by enzymatic reaction, the NADPH-supported activities of steroid 17 alpha-hydroxylase and C-17-C-20 lyase were further stimulated as compared with the addition of NADH, and this stimulation was suppressed by the antibody against cytochrome b5. These results suggest that cytochrome b5, together with 3 beta-hydroxy-delta 5-steroid dehydrogenase, contributes to the activities of steroid 17 alpha-hydroxylase and C-17-C-20 lyase in the testicular microsomal fraction.

3-Hydroxysteroid Dehydrogenases↗
PubMed1984

Oxygenation of 18-hydroxycorticosterone as the final reaction for aldosterone biosynthesis.

Incubation of 18-hydroxycorticosterone with the sonicated mitochondrial preparation of bovine adrenal glomerulosa tissue leads to the production of aldosterone, as measured by radioimmunoassay. The in vitro production of aldosterone from 18-hydroxycorticosterone requires both molecular oxygen and NADPH, and is inhibited by carbon monoxide. Cytochrome P-450 inhibitors such as metyrapone, SU 8000, SU 10603, SKF 525A, amphenone B and spironolactone decrease the biosynthesis of aldosterone from 18-hydroxycorticosterone. These results support the conclusion that the final reaction in aldosterone synthesis from 18-hydroxycorticosterone is catalyzed by an oxygenase, but not by 18-hydroxysteroid dehydrogenase. By the same preparation, the production of [3H]aldosterone but not [3H]18-hydroxycorticosterone from [1,2-3H]corticosterone is decreased in a dose-dependent manner by addition of non-radioactive 18-hydroxycorticosterone.

18-Hydroxycorticosterone↗
PubMed1984

Chemical modification of tyrosine residues in active-site of human placental estradiol 17 beta-dehydrogenase by tetranitromethane.

The native estradiol 17 beta-dehydrogenase purified from human placenta was rapidly inactivated by tetranitromethane, which is a reagent for chemical modification of tyrosine and cysteine residues. The inactivation followed pseudo-first-order reaction kinetics, and the activity was partially recovered by addition of dithiothreitol. On the other hand, the enzyme sulfhydryl-blocked by 5,5'-dithiobis(2-nitrobenzoic acid) was treated with tetranitromethane, and the activity was assayed in the presence of dithiothreitol. Tetranitromethane inactivated the enzyme in a time-dependent manner, following pseudo-first-order kinetics. The rate of inactivation was significantly decreased by addition of NADP(H), 2'-AMP, 5'-ATP, 2',5'-ADP, 3-pyridine aldehyde-DPN and 3-acetylpyridine-DPN(reduced form). These results suggest that the tyrosyl residues are located at or near the cofactor-binding site of the estradiol 17 beta-dehydrogenase and play an essential role in the catalytic function of the enzyme.

17-Hydroxysteroid Dehydrogenases↗
PubMed1983

Affinity labeling of arginyl residues at the catalytic region of estradiol 17 beta-dehydrogenase from human placenta by 16-oxoestrone.

16-Oxoestrone inhibited competitively the activity of estradiol 17 beta-dehydrogenase from human placenta against estradiol in phosphate buffer (pH 7.2), suggesting reversible binding of 16-oxoestrone to the substrate-binding site. 16-Oxoestrone irreversible inactivated the estradiol 17 beta-dehydrogenase in borate buffer (pH 8.5) in a time-dependent manner, following pseudo-first-order kinetics. The rate constant (k3) obtained for the inactivation by 16-oxoestrone was 8.3 x 10(-4) s-1. The rate of inactivation was significantly decreased by addition of estrone, estradiol, estriol, NAD(H) and NADP+. Also, the rate was reduced markedly by 2'AMP, 5'ATP and 2',5' ADP, but not by NMN(H) and 3-pyridinealdehyde adeninediphospho nucleotide. The inactivation by 16-oxoestrone was neither prevented by sodium azide nor influenced by light. From these data, 16-oxoestrone, an alpha-dicarbonyl steroid, was suggested to inactive estradiol 17 beta-dehydrogenase by modification of arginyl residues located around the substrate-binding site of the enzyme. Biphasic inactivation of the enzyme by 16-oxoestrone was observed with an increase of modified arginyl residues. The first phase of the inactivation was regarded as an affinity labeling of the arginyl residues at or near the substrate-binding site of the enzyme. Stoichiometry of the inactivation indicated that two arginyl residues were essential for maintenance of the enzyme activity. The second phase was considered as chemical modification of the arginyl residues outside of the catalytic region of the enzyme.

17-Hydroxysteroid Dehydrogenases↗
PubMed1983

Relative in vitro effectiveness of 17 alpha, 20 beta-dihydroxy-4-pregnen-3-one and other pregnene derivatives on germinal vesicle breakdown in oocytes of ayu (Plecoglossus altivelis), amago salmon (Oncorhynchus rhodurus), rainbow trout (Salmo gairdneri), and goldfish (Carassius auratus).

The relative effectiveness of several pregnene derivatives, which had previously been identified in the ovaries of ayu (Plecoglossus altivelis), on germinal vesicle breakdown (GVBD) was investigated in vitro using folliculated oocytes of four species of teleosts, ayu, amago salmon (Oncorhynchus rhodurus), rainbow trout (Salmo gairdneri), and goldfish (Carassius auratus). Although some species differences existed in the relative effectiveness of each steroid on GVBD, 17 alpha, 20 beta-dihydroxy-4-pregnen-3-one (17 alpha, 20 beta-diOHprog) was consistently the most potent inducer of final oocyte maturation. Both progesterone and 17 alpha-hydroxyprogesterone were effective at relatively high concentrations. Of the 5 beta-reduced metabolites, 17 alpha, 20 beta-dihydroxy-5 beta-pregnan-3-one was almost as effective as 17 alpha, 20 beta-diOHprog in oocytes of amago salmon and rainbow trout, while the other 5 beta-reduced compounds (3 alpha-hydroxy-5 beta-pregnan-20-one, 17 alpha-hydroxy-5 beta-pregnane-3,20-dione, 3 alpha, 17 alpha-dihydroxy-5 beta-pregnan-20-one, 5 beta-pregnane-3 alpha, 17 alpha, 20 beta-triol, and 5 beta-pregnane-3 beta, 17 alpha, 20 beta-triol) were almost or totally ineffective at the concentrations tested (1-0.001 micrograms/ml). These bioassay results, together with previous findings on the capacity of the ovary to produce 17 alpha, 20 beta-diOHprog, indicate that 17 alpha, 20 beta-diOHprog is the natural maturation-inducing steroid hormone common to three species of Salmoniformes, ayu, amago salmon, and rainbow trout. These results, however, only suggest that 17 alpha, 20 beta-diOHprog is involved in maturation of goldfish oocytes, since supportive physiological and biochemical data are lacking. Possible regulatory roles of 5 beta-reduced metabolites on steroid-induced oocyte maturation are discussed.

Animals↗
PubMed1983

Photochemical inactivation of human placental estradiol 17 beta-dehydrogenase in the presence of 2,3-butanedione.

Estradiol 17 beta-dehydrogenase of human placenta was rapidly inactivated by 2,3-butanedione under u.v. light, and no protection against the inactivation was observed in the presence of sodium azide. Under ordinary laboratory illumination, the inactivation was biphasically progressed in time-dependent and concentration-dependent manners, while a partial protection from the inactivation was indicated by sodium azide. These results suggest that the inactivation mechanism of the dehydrogenase by 2,3-butanedione under laboratory illumination is different from that under u.v. light. Therefore, the inactivation under laboratory illumination proceeded by a reaction with excited singlet molecular oxygen (1 delta g or 1 sigma +g states), and that under u.v. light was caused by a reaction of substrate with triplet sensitizer. In the presence of NADP+, the inactivation of the enzyme by 2,3-butanedione was markedly reduced. The maximum protection by NADP+ was about 80% of the initial enzyme activity. Amino acid analysis of the enzyme treated with 2,3-butanedione under laboratory illumination showed that the modified enzyme contained considerably less of the following amino acids than the native enzyme: histidine, arginine, threonine, methionine, tyrosine and leucine. In addition, other dicarbonyl reagents, 1,4-dibromo-2,3-butanedione, 1-phenyl-1,2-propanedione, phenylglyoxal, 16-oxoestrone, 1,2-cyclohexanedione, 2,4-pentanedione and glyoxal were found to decrease the dehydrogenase activity in various degree.

17-Hydroxysteroid Dehydrogenases↗
PubMed1983

Functional site of human placental estradiol 17 beta-dehydrogenase involves tyrosine residues, as evidenced by reaction to p-nitrobenzenesulfonyl fluoride.

Native estradiol 17 beta-dehydrogenase (EC 1.1.1.62) from human placenta was inactivated in time dependent manner by p-nitrobenzenesulfonyl fluoride (NBSF), which is a reagent for chemical modification of tyrosine. The sulfhydryl-blocked enzyme by 5,5'-dithio-bis(2-nitrobenzoic acid) (DTNB) was also reacted with NBSF more slowly in pseudo-first-order kinetics. After the sequential treatments with DTNB, NBSF and dithiothreitol (DTT), the enzyme in which tyrosine residues alone were modified was isolated, and its activity was decreased. These results suggest that tyrosyl residues of the estradiol 17 beta-dehydrogenase from human placenta are located at or near its catalytic site, and play a functional role in the enzyme reaction.

17-Hydroxysteroid Dehydrogenases↗
PubMed1983

Acute decrease by human chorionic gonadotropin of the activity of preovulatory ovarian 17 alpha-hydroxylase and C-17-C-20 lyase is due to decrease of microsomal cytochrome P-450 through de novo synthesis of ribonucleic acid and protein.

Female rats were treated with 10 IU pregnant mare's serum gonadotropin (PMSG) on the 21st day after birth, and 53 h later with 20 IU human CG (hCG) in order to investigate the mechanism of action of hCG upon ovarian 17 alpha-hydroxylase and C-17-C-20 lyase. The activity of ovarian 17 alpha-hydroxylase and C-17-C-20 lyase was severely decreased within 6 h after the injection of hCG. However, treatment with cycloheximide or puromycin before the hCG injection prevented the decrease in the activity of these enzymes by hCG. Actinomycin D pretreatment prevented the hCG-induced decrease of C-17-C-20 lyase activity. In correlation with the changes in these enzyme activities induced by hCG, the concentration of ovarian microsomal cytochrome P-450 decreased to barely detectable level after hCG treatment; this decrease was also prevented by pretreatment with cycloheximide. When the cytochrome P-450 obtained from the PMSG-treated rats was subjected to spectrometric analysis of binding with progesterone and 17 alpha-hydroxy-progesterone, type I spectra were obtained for both steroids, indicating that the steroids bound to the cytochrome as substrate. Testosterone, a substrate for aromatase, showed very limited binding to the cytochrome, however. On the other hand, the microsomes obtained from the PMSG + hCG treated ovaries showed no type I spectrum with progesterone and 17 alpha-hydroxy-progesterone. The activity of NADPH-cytochrome c reductase in the ovarian microsomes was not significantly influenced by the hCG treatment. These results indicate that the acute decrease of ovarian 17 alpha-hydroxylase and C-17-C-20 lyase activity by hCG treatment was caused through the decrease of cytochrome P-450 and is correlated with de novo synthesis of RNA and protein.

Aldehyde-Lyases↗