当前位置： SCI文献检索 > ARCHIVES OF BIOCHEMISTRY AND BIOPHYSICS期刊下所有文献 > Regioselective hydroxylation of prostaglandins by constitutive forms of cytochrome P-450 from rat liver: formation of a novel metabolite by a female-specific P-450.

Regioselective hydroxylation of prostaglandins by constitutive forms of cytochrome P-450 from rat liver: formation of a novel metabolite by a female-specific P-450.

Abstract：

:Previous studies demonstrated that liver microsomes from untreated rats catalyze the omega, omega-1, and omega-2 hydroxylation of prostaglandins [K. A. Holm, R. J. Engell, and D. Kupfer (1985) Arch. Biochem. Biophys. 237, 477-489]. The current study examined the regioselectivity of hydroxylation of PGE1 and PGE2 by purified forms of P-450 from untreated male and female rat liver microsomes. PGE1 was incubated with a reconstituted system containing cytochrome P-450 RLM 2, 3, 5, 5a, 5b, 6, or f4, NADPH-P-450 reductase, and dilauroylphosphatidylcholine in the presence or absence of cytochrome b5. Among the P-450 forms examined, only RLM 5 (male specific), 5a (present in both sexes), and f4 (female specific) yielded high levels of PGE hydroxylation. With PGE1, RLM 5 catalyzed solely the omega-1 hydroxylation and 5a catalyzed primarily the omega-1 and little omega and omega-2 hydroxylation. By contrast, f4 effectively hydroxylated PGE1 and PGE2 at the omega-1 and at a novel site. Based on retention on HPLC and on limited mass fragmentation, we speculate that this site is omega-3 (i.e., 17-hydroxylation). Kinetic analysis of PGE1 hydroxylation demonstrated that the affinity of f4 for PGE1 is approximately 100-fold higher than that of RLM 5; the Km values for f4, monitoring 19- and 17-hydroxylation of PGE1, were about 10 microM. Surprisingly, cytochrome b5 stimulated the activity of RLM 5a and f4, but not that of RLM 5. Hydroxylation of PGE2 by RLM 5 was at the omega, omega-1, and omega-2 sites, demonstrating a lesser regioselectivity than with PGE1. These findings show that the constitutive P-450s differ dramatically in their ability to hydroxylate PGs, in their regioselectivity of hydroxylation, and in their cytochrome b5 requirement.

journal_name

Arch Biochem Biophys

journal_title

Archives of biochemistry and biophysics

authors

Kupfer D,Jansson I,Favreau LV,Theoharides AD,Schenkman JB

doi

10.1016/0003-9861(88)90117-8

subject

Has Abstract

pub_date

1988-02-15 00:00:00

pages

186-95

issue

eissn

0003-9861

issn

1096-0384

pii

0003-9861(88)90117-8

journal_volume

261

pub_type

杂志文章

在线工具

Regioselective hydroxylation of prostaglandins by constitutive forms of cytochrome P-450 from rat liver: formation of a novel metabolite by a female-specific P-450.