152-58-9Relevant articles and documents
Danazol Inhibits Human Adrenal 21- and 11β-Hydroxylation in vitro
Barbieri, Robert L.,Osathanondh, Rapin,Canick, Jacob A.,Stillman, Robert J.,Ryan, Kenneth J.
, p. 251 - 263 (1980)
The effects of danazol on steroidogenesis in vitro in the 16-20 week old human fetal adrenal were examined by studying: 1) danazol binding to adrenal microsomal and mitochondrial cytochrome P-450, and 2) enzyme kinetics of danazol inhibition of the adrenal microsomal 21-hydroxylase and the mitochondrial 11β-hydroxylase.The addition of danazol to preparations of adrenal microsomes or mitochondria elicited a type I cytochrome P-450 binding spectrum.Danazol bound to microsomal cytochrome P-450 with a high affinity apparent spectral dissociation constant (KS) of 1 μM and with a lower affinity K'S of 10 μM.Danazol bound to mitochondrial cytochrome P-450 with a KS of 5 μM.In addition, danazol competitively inhibited the microsomal 21-hydroxylase (apparent enzymatic inhibition constant KI = 0.8 μM) and the mitrochondrial 11β-hydroxylase (KI = 3 μM).These findings demonstrate that low concentrations of danazol directly inhibit steroidogenesis in the human fetal adrenal in vitro.
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v.Euw,Reichstein
, p. 1140,1142 (1941)
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Inherent steroid 17α,20-lyase activity in defunct cytochrome P450 17A enzymes
Gonzalez, Eric,Johnson, Kevin M.,Pallan, Pradeep S.,Phan, Thanh T.N.,Zhang, Wei,Lei, Li,Wawrzak, Zdzislaw,Yoshimoto, Francis K.,Egli, Martin,Peter Guengerich
, p. 541 - 556 (2018)
Cytochrome P450 (P450) 17A1 catalyzes the oxidations of progesterone and pregnenolone and is the major source of androgens. The enzyme catalyzes both 17α-hydroxylation and a subsequent 17α,20-lyase reaction, and several mechanisms have been proposed for the latter step. Zebrafish P450 17A2 catalyzes only the 17α-hydroxylations. We previously reported high similarity of the crystal structures of zebrafish P450 17A1 and 17A2 and human P450 17A1. Five residues near the heme, which differed, were changed. We also crystallized this five-residue zebrafish P450 17A1 mutant, and the active site still resembled the structure in the other proteins, with some important differences. These P450 17A1 and 17A2 mutants had catalytic profiles more similar to each other than did the wildtype proteins. Docking with these structures can explain several minor products, which require multiple enzyme conformations. The 17α-hydroperoxy (OOH) derivatives of the steroids were used as oxygen surrogates. Human P450 17A1 and zebrafish P450s 17A1 and P450 17A2 readily converted these to the lyase products in the absence of other proteins or cofactors (with catalytically competent kinetics) plus hydroxylated 17α-hydroxysteroids. The 17α-OOH results indicate that a "Compound I" (FeO3+) intermediate is capable of formation and can be used to rationalize the products. We conclude that zebrafish P450 17A2 is capable of lyase activity with the 17α-OOH steroids because it can achieve an appropriate conformation for lyase catalysis in this system that is precluded in the conventional reaction.
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Reichstein,v.Euw
, p. 1258 (1940)
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Conversion of progesterone to corticosteroids by the midterm fetal adrenal and kidney
McShane,deM. Fencl
, p. 299 - 310 (1983)
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Human cytochrome P450 21A2, the major steroid 21-hydroxylase: Structure of the enzyme?progesterone substrate complex and rate-limiting C-H bond cleavage
Pallan, Pradeep S.,Wang, Chunxue,Lei, Li,Yoshimoto, Francis K.,Auchus, Richard J.,Waterman, Michael R.,Guengerich, F. Peter,Egli, Martin
, p. 13128 - 13143 (2015)
Cytochrome P450 (P450) 21A2 is the major steroid 21-hydroxylase, and deficiency of this enzyme is involved in ～95% of cases of human congenital adrenal hyperplasia, a disorder of adrenal steroidogenesis. A structure of the bovine enzyme that we published previously (Zhao, B., Lei, L., Kagawa, N., Sundaramoorthy, M., Banerjee, S., Nagy, L. D., Guengerich, F. P., and Waterman, M. R. (2012) Three-dimensional structure of steroid 21-hydroxylase (cytochrome P450 21A2) with two substrates reveals locations of disease-associated variants. J. Biol. Chem. 287, 10613-10622), containing two molecules of the substrate 17α-hydroxyprogesterone, has been used as a template for understanding genetic deficiencies. We have now obtained a crystal structure of human P450 21A2 in complex with progesterone, a substrate in adrenal 21-hydroxylation. Substrate binding and release were fast for human P450 21A2 with both substrates, and pre-steady-state kinetics showed a partial burst but only with progesterone as substrate and not 17α-hydroxyprogesterone. High intermolecular non-competitive kinetic deuterium isotope effects on both kcat and kcat/Km, from 5 to 11, were observed with both substrates, indicative of rate-limiting C-H bond cleavage and suggesting that the juxtaposition of the C21 carbon in the active site is critical for efficient oxidation. The estimated rate of binding of the substrate progesterone (kon 2.4 × 107 M-1 s-1) is only ～2-fold greater than the catalytic efficiency (kcat/Km = 1.3 × 107 M-1 s-1) with this substrate, suggesting that the rate of substrate binding may also be partially rate-limiting. The structure of the human P450 21A2-substrate complex provides direct insight into mechanistic effects of genetic variants.
P450BM3 on steroids: The Swiss Army Knife P450 enzyme just gets better
Wong, Luet-Lok
scheme or table, p. 2537 - 2539 (2012/05/07)
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