Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.1.1.3 (HSD)
 3,464 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Transport properties of active enzyme species can be studied effectively by layering a small band of enzyme-containing sample on a gel chromatographic column previously saturated with substrate. The column is optically scanned at successive time intervals to yield profiles representing the appearance of chromophoric product or disappearnce of chromophoric substrate. These profiles permit determination of the specific activity and rate of transport of the active species. Initial studies on mechanic of the technique establish the feasibility of accurately determining transport properties of active enzyme species chromatographed on gel columns. Illustrative results are presented for L-glutamate dehydrogenase and for homoserine dehydrogenase studied in both forward and reverse reactions. It is shown that the partititon cross sections derived from the rates of motion of catalytic activity are the same as those determined by equilibrium saturation experiments which directly measure the degree of partitioning by the protein. These results establish the validity of the technique for a variety of future studies. Active enzyme gel chromatography appears comparable in precision to the active enzyme sedimentation technique at current stages of development.
Biophys Chem 1976 Sep
PMID:Active enzyme gel chromatography. I. Experimental aspects. 1 19

The ability of cultured midpregnancy mouse ovarian cells to synthesize progesterone de novo and from oxogenous pregnenolone has been assessed. The conversion of pregnenolone to progesterone is almost completely blocked by cyanoketone, a known inhibitor of delta5,3beta-hydroxysteroid dehydrogenase (3beta-HSD) activity, but is unaffected by aminoglutethimide, which inhibits the cholesterol side-chain cleavage enzyme complex (desmolase). Since there is little metabolism of the formed progesterone, the ability of ovarian cells to convert exogenous pregnenolone to progesterone in vitro reflects the activity of 3beta-HSD in these cells. Cultured ovarian cells are also capable of endogenous progesterone production in the absence of added pregnenolone, although the absolute amount of progesterone produced is considerably less than that produced from exogenous pregnenolone. Since endogenous progesterone accumulation is almost completely blocked by the addition of aminoglutethimide to the culture medium, it is concluded that this response does represent de novo progesterone synthesis. Neither bovine luteinizing hormone (LH) nor human chorionic gonadotrophin (hCG) affects 3beta-HSD activity in cultured ovarian cells. The ability of the cells to secrete or to further metabolize the progesterone formed is also unaffected. However, both LH and hCG stimulate endogenous progesterone production within one hour of their addition to the culture medium. The stimulation, 2-10 fold in several experiments, can be maintained for at least six days of culture, and is not a result of an increase in the growth rate of the ovarian cells. As would be expected, the stimulation is blocked by the addition of aminoglutethimide to the culture medium. Taken together, these facts suggest that gonadotrophic hormones stimulate progesterone production by ovarian cells specifically by their action at steps prior to the conversion of pregnenolone to progesterone.
Endocrinology 1976 Sep
PMID:Gonadotrophin stimulation of progesterone synthesis by midpregnancy mouse ovarian cells in vitro. 95 70

17 beta-Hydroxysteroid dehydrogenase (17 beta HSD) deficiency is a rare cause of male pseudohermaphroditism, but is a frequent disorder among a highly inbred Arab population in the Gaza strip. Affected individuals are born and reared as females until puberty, when marked virilization occurs, leading in many cases to the spontaneous adoption of a male gender role. To investigate the mechanisms and site(s) of androgen production, we determined the gonadal and extragonadal steroid patterns in two postpubertal male pseudohermaphroditism patients, who were castrated and reared as females. Before castration, both patients had very high plasma levels of androstenedione (delta 4-A), normal or moderately low levels of testosterone (T), and significantly elevated delta 4-A/T ratios (P less than 0.01). Dihydrotestosterone (DHT) levels were normal or high, while the DHT/T ratios were lower than normal (P less than 0.01), suggesting enhanced 5 alpha-reductase activity. These abnormalities were much more severe in spermatic venous blood. 17 beta HSD deficiency was also found in the delta 5-pathway, by high dehydroepiandrosterone (DHEA) levels and very high dehydroxyepiandrosterone/delta 5-androstenediol (DHEA/delta 5-diol) ratios, and in peripheral tissue metabolites, by very high androsterone glucuronide/3 alpha-androstanediol glucuronide ratios (P less than 0.01). The estrogen pathway was also impaired (P less than 0.01), even though both estrone and estradiol levels were elevated. Gonadectomy significantly reduced all androgens and estrogens (P less than 0.01), but when compared to 42 castrated controls, both patients had lower delta 4-A and higher T levels. The delta 4-A/T ratio was lower than that in controls, indicating normal to enhanced extragonadal 17 beta HSD activity. A similar pattern was observed in the delta 5- and estrogen pathways. DHT levels were within normal limits, and 3 alpha-diol was moderately decreased. These data suggest that testicular 17 beta HSD activity is under a different genetic control from that in extragonadal tissues. Affected males lack the testicular enzyme, but their extragonadal 17 beta HSD activity is normal or enhanced. Together with enhanced 5 alpha-reductase activity, this represents a highly efficient compensatory mechanism for androgen and estrogen production after puberty.
J Clin Endocrinol Metab 1992 Sep
PMID:Mechanisms of androgen production in male pseudohermaphroditism due to 17 beta-hydroxysteroid dehydrogenase deficiency. 132 74

The regulation of steroid production by the placenta and fetal membranes is important for both the maintenance of pregnancy and the timing of parturition. 3 beta-Hydroxy-5-ene-steroid dehydrogenase/delta 5----delta 4-isomerase (3 beta HSD) catalyzes an obligatory step in the biosynthesis of steroid hormones. We have determined the localization of 3 beta HSD in the human placenta, fetal membranes, and umbilical cord throughout gestation by immunohistochemical analysis, using a polyclonal antibody raised in rabbits against a purified preparation of human placental 3 beta HSD. In placenta, immunoreactive (IR-) 3 beta HSD was localized in the syncytiotrophoblast and intermediate trophoblast cells at both villous and extravillous sites, but not in cytotrophoblast cells from 6 weeks gestation to term. At 6-7 weeks gestation, IR-3 beta HSD was distributed in the cytoplasm of syncytiotrophoblast in about half of placental villi. By 12-14 weeks, the syncytiotrophoblast of all placental villi stained positively for 3 beta HSD. In the fetal membranes, strong IR-3 beta HSD staining was found in the trophoblast and reticular layers of chorion and in invasive trophoblast cells in decidua, and weakly in decidual stromal cells and amniotic epithelium. No IR-3 beta HSD was found in amnion on the placental plate, but in the umbilical cord, IR-3 beta HSD was present in the amniotic epithelium and also in fibroblast cells in Warton's jelly. These observations demonstrate that the localization of 3 beta HSD immunoreactivity and, therefore, the presumed sites of delta 5- to delta 4-steroid interconversion throughout gestation are principally the syncytiotrophoblast and intermediate trophoblast cells in placenta and the trophoblast cells in chorion and decidua in fetal membranes.
J Clin Endocrinol Metab 1992 Sep
PMID:Immunohistochemical localization of 3 beta-hydroxy-5-ene-steroid dehydrogenase/delta 5----delta 4 isomerase in human placenta and fetal membranes throughout gestation. 138 75

Adult male rats were given s.c. injections of melatonin (400 micrograms/100 g body weight per day) for 14 days. On day 15, the weights of the testis and accessory sex organs were less, testicular 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD) activity was inhibited, spermatogenesis was suppressed and serum levels of gonadotrophins, testosterone and alpha 2u-globulin were decreased compared with control animals injected with vehicle. In a third group of rats given the same dose of melatonin for 14 days, administration of dihydrotestosterone (DHT) at a dose of 25 micrograms/100 g body weight per day on days 8-14 resulted in serum levels of alpha 2u-globulin, FSH, LH and testosterone and testicular 17 beta-HSD activity similar to those seen in vehicle-injected control animals. Weights of the testes and accessory sex organs and spermatogenesis were normal after administration of DHT in melatonin-treated rats. In another group of rats, the depressive effects of melatonin treatment on plasma gonadotrophins were reversed by the administration of alpha 2u-globulin on days 8-14. It was concluded that treatment with DHT prevents the depressive action of melatonin on testicular function by inducing the synthesis of alpha 2u-globulin.
J Endocrinol 1990 Sep
PMID:Effect of dihydrotestosterone on serum concentrations of alpha 2u-globulin and on spermatogenesis in melatonin-treated rats. 169 6

To evaluate the use of hypertonic saline/dextran solutions in the prehospital resuscitation of severely injured patients, we administered 250 mL of either 7.5% sodium chloride/dextran 70 (HSD) (n = 83) or lactated Ringer's solution (n = 83), followed by conventional isotonic fluids, to 166 trauma patients with systolic blood pressures less than or equal to 100 mm Hg, in a prospective, randomized, double-blinded clinical trial. Patients in the sodium chloride/dextran 70 group required less fluid before hospitalization and arrived in the emergency department with higher systolic blood pressures than patients in the lactated Ringer's solution group. The rate of survival to hospital discharge for the entire cohort was 64% for patients in the sodium chloride/dextran 70 group vs 59% for patients in the lactated Ringer's solution group. The rate of survival to hospital discharge for the patients with severe head injuries was 32% for the sodium chloride/dextran 70 group vs 16% for the lactated Ringer's solution group. Actuarial survival for patients with severe head injuries in the sodium chloride/dextran 70 group compared with patients with severe head injuries in the lactated Ringer's solution group did not quite reach statistical significance. There were no adverse side effects associated with sodium chloride/dextran 70 administration. Administration of small volumes of sodium chloride/dextran 70 before hospitalization increased the blood pressure of severely injured patients more effectively than did lactated Ringer's solution and showed tendencies toward improving survival in the patients with severe head injuries.
Arch Surg 1991 Sep
PMID:7.5% sodium chloride/dextran for resuscitation of trauma patients undergoing helicopter transport. 171 43

Homogeneous 3 alpha-hydroxysteroid dehydrogenase (3 alpha-HSD; EC 1.1.1.50) of rat liver cytosol is a monomeric (Mr 34000) NAD(P)+ dependent oxidoreductase which displays 9-, 11- & 15-hydroxyprostaglandin dehydrogenase activity. The enzyme is potently inhibited by nonsteroidal anti-inflammatory drugs (NSAIDs), suggesting that 3 alpha-HSD may be a target enzyme for NSAIDs. A monospecific, polyclonal anti-sera raised against the purified enzyme was used to screen a lambda gt11 expression library and oligonucleotide probes complementary to the 5' and 3' ends of immunopositive clones were used to isolate a 2.1 kb full-length cDNA. Digestion of the full-length cDNA with Eco RI generated two fragments of 1.1 and 1.0 kb in length. Both fragments were subcloned into pGEM3 and partially sequenced. The 1.1 kb fragment contains the C-terminus of 3 alpha-HSD which was confirmed by an in-frame stop codon and comparison of the predicted amino acid sequence to peptide sequence obtained from two endo lys-C peptides of 3 alpha-HSD. The 1.0 kb fragment is 5' to the 1.1 kb fragment and is sufficient in length to contain the remainder of the entire open reading frame for 3 alpha-HSD. Dideoxysequencing reveals significant sequence homology with bovine lung prostaglandin PGF2 alpha synthase. These findings support the role 3 alpha-HSD in inflammation and suggest that hydroxysteroid dehydrogenases, hydroxyprostaglandin dehydrogenases and prostaglandin F2 alpha synthase may be members of a common gene family.
Agents Actions 1991 Sep
PMID:Isolation and partial characterization of a full-length cDNA clone for 3 alpha-hydroxysteroid dehydrogenase: a potential target enzyme for nonsteroidal anti-inflammatory drugs. 179 46

The regulation of mRNA levels for delta 5-3 beta-hydroxysteroid dehydrogenase/delta 5----delta 4-isomerase (3 beta HSD), 17 alpha-hydroxylase/C17-20 lyase cytochrome P450 (P450(17 alpha] and cholesterol side-chain cleavage cytochrome P450 (P450scc) was studied in primary cultures of mouse Leydig cells. Treatment of Leydig cells with 8-bromo-cAMP (cAMP) was essential for expression of P450(17 alpha) mRNA, but not for 3 beta HSD. Treatment with cAMP caused a decrease in basal levels of 3 beta HSD mRNA. The addition of aminoglutethimide (AG), an inhibitor of cholesterol metabolism, to the cAMP-treated cultures resulted in increased expression of both 3 beta HSD and P450(17 alpha) mRNA levels. The addition of testosterone or the androgen agonist mibolerone to cAMP- plus AG-treated cultures reduced 3 beta HSD and P450(17 alpha) mRNA to levels comparable to those observed when cells were treated with cAMP only. The glucocorticoid dexamethasone reduced both basal and cAMP- plus AG-induced increases in 3 beta HSD mRNA, but not in P450(17 alpha) mRNA. Estradiol at a concentration of 1 microM had no effect on cAMP- plus AG-induced 3 beta HSD or P450(17 alpha) mRNA levels. The role of protein synthesis in mediating the cAMP induction of 3 beta HSD, P450(17 alpha), and P450scc was investigated. The addition of cycloheximide (10 micrograms/ml) to cAMP-treated cultures for 24 h completely suppressed both constitutive and cAMP-induced 3 beta HSD mRNA levels. Cycloheximide also repressed cAMP-induced levels of P450(17 alpha) to 12% of levels observed in the absence of cycloheximide. In sharp contrast, 24-h treatment with cycloheximide did not suppress cAMP induction of P450scc mRNA, but reduced basal levels by approximately 50%. A time course of induction by cAMP (50 microM) of P450(17 alpha) and P450scc mRNA showed very similar rates of increase in P450(17 alpha) and P450scc mRNA, with the greatest increase occurring between 12 and 24 h of treatment. The results of the study demonstrate that in normal mouse Leydig cells steady state levels of mRNA for 3 beta HSD, P450(17 alpha), and P450scc are differentially regulated. cAMP is required for maximal levels of all three mRNAs. There is high constitutive expression of 3 beta HSD and P450scc mRNA, while expression of P450(17 alpha) mRNA is absolutely dependent on cAMP stimulation. Endogenously produced testosterone negatively regulates the expression of cAMP-induced P450(17 alpha) and 3 beta HSD, while the glucocorticoid dexamethasone negatively regulates 3 beta HSD and P450scc.(ABSTRACT TRUNCATED AT 400 WORDS)
Endocrinology 1991 Sep
PMID:Multiple mechanisms for regulation of 3 beta-hydroxysteroid dehydrogenase/delta 5----delta 4-isomerase, 17 alpha-hydroxylase/C17-20 lyase cytochrome P450, and cholesterol side-chain cleavage cytochrome P450 messenger ribonucleic acid levels in primary cultures of mouse Leydig cells. 187 81

The Type I (mineralocorticoid) receptor has identical affinities in vitro for cortisol and aldosterone. It has been suggested that the selective role of aldosterone in regulating sodium homeostasis relies on the microsomal enzyme 11 beta-hydroxysteroid dehydrogenase (11-HSD). This enzyme converts cortisol to its inactive metabolite, cortisone, preventing cortisol from binding to the Type I receptor. We have isolated human cDNA clones encoding 11-HSD from a human testis cDNA library by hybridization with a previously isolated rat 11-HSD cDNA clone. The cDNA contains an open reading frame of 876 bases, which predicts a protein of 292 amino acids. The sequence is 77% identical at the amino acid level to rat 11-HSD cDNA. The mRNA is widely expressed, but the level of expression is highest in the liver. Hybridization of the human 11-HSD cDNA to a human-hamster hybrid cell panel localized the single corresponding HSD11 gene to chromosome 1. This gene was isolated from a chromosome 1 specific library using the cDNA as a probe. HSD11 consists of 6 exons and is at least 9 kilobases long. The data developed in this study should be applicable to the study of patients with hypertension due to apparent mineralocorticoid excess, a deficiency in 11-HSD activity.
J Biol Chem 1991 Sep 05
PMID:The human gene for 11 beta-hydroxysteroid dehydrogenase. Structure, tissue distribution, and chromosomal localization. 188 95

Rat liver 3 alpha-hydroxysteroid dehydrogenase (3 alpha-HSD) (EC 1.1.1.50) is an NAD(P)(+)-dependent oxidoreductase that is potently inhibited at its active site by non-steroidal anti-inflammatory drugs (NSAIDs). Initial-velocity and product-inhibition studies performed in either direction at pH 7.0 are consistent with a sequential ordered Bi Bi mechanism in which pyridine nucleotide binds first and leaves last. This mechanism is supported by fluorescence titrations of the E-NADH complex, and by the failure to detect the binding of either [3H]androsterone or [3H]androstanedione to free enzyme by equilibrium dialysis. Dead-end inhibition studies with NSAIDs also support this mechanism. Initial-velocity studies with indomethacin show that this drug is an uncompetitive inhibitor against NAD+, but a potent competitive inhibitor against androsterone, indicating the ordered formation of an E.NAD+.indomethacin complex. Calculation of the individual rate constants reveals that the binding and release of pyridine nucleotide is rate-limiting and that isomerization of the central complex is favoured in the forward direction. Equilibrium dialysis experiments with [14C]indomethacin reveal the presence of two abortive NSAID complexes, a high-affinity ternary complex corresponding to E.NAD+.indomethacin (Kd = 1-2 microM for indomethacin) and a low-affinity binary complex corresponding to E.indomethacin (Kd = 22 microM for indomethacin). Since indomethacin has a low affinity for free enzyme, the formation of this abortive binary complex does not complicate kinetic measurements which are made in the presence of NAD+, but may contribute to the inhibition of the enzyme by NSAIDs. Using either pro-R-[4-3H]NADH or pro-S-[4-3H]NADH as cofactor, radiolabelled androsterone was formed only when the pro-R-[4-3H]NADH was used, confirming that purified 3 alpha-HSD is a Class A dehydrogenase.
Biochem J 1991 Sep 15
PMID:The kinetic mechanism catalysed by homogeneous rat liver 3 alpha-hydroxysteroid dehydrogenase. Evidence for binary and ternary dead-end complexes containing non-steroidal anti-inflammatory drugs. 189 69


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