Identification of CYP4F8 in human seminal vesicles as a prominent 19-hydroxylase of prostaglandin endoperoxides.
A novel cytochrome P450, CYP4F8, was recently cloned from human seminal vesicles. CYP4F8 was expressed in yeast. Recombinant CYP4F8 oxygenated arachidonic acid to (18R)-hydroxyarachidonate, whereas prostaglandin (PG) D(2), PGE(1), PGE(2), PGF(2alpha), and leukotriene B(4) appeared to be poor substrates. Three stable PGH(2) analogues, 9,11-epoxymethano-PGH(2) (U-44069), 11, 9-epoxymethano-PGH(2) (U-46619), and 9,11-diazo-15-deoxy-PGH(2) (U-51605) were rapidly metabolized by omega2- and omega3-hydroxylation. U-44069 was oxygenated with a V(max) of approximately 260 pmol min(-)(1) pmol P450(-1) and a K(m) of approximately 7 micrometer. PGH(2) decomposes mainly to PGE(2) in buffer and to PGF(2alpha) by reduction with SnCl(2). CYP4F8 metabolized PGH(2) to 19-hydroxy-PGH(2), which decomposed to 19-hydroxy-PGE(2) in buffer and could be reduced to 19-hydroxy-PGF(2alpha) with SnCl(2). 18-Hydroxy metabolites were also formed (approximately 17%). PGH(1) was metabolized to 19- and 18-hydroxy-PGH(1) in the same way. Microsomes of human seminal vesicles oxygenated arachidonate, U-44069, U-46619, U-51605, and PGH(2), similar to CYP4F8. (19R)-Hydroxy-PGE(1) and (19R)-hydroxy-PGE(2) are the main prostaglandins of human seminal fluid. We propose that they are formed by CYP4F8-catalyzed omega2-hydroxylation of PGH(1) and PGH(2) in the seminal vesicles and isomerization to (19R)-hydroxy-PGE by PGE synthase. CYP4F8 is the first described hydroxylase with specificity and catalytic competence for prostaglandin endoperoxides.
Bylund
J
J
Division of Biochemical Pharmacology, Department of Pharmaceutical Biosciences, Uppsala Biomedical Centre, Uppsala University, SE-751 24 Uppsala, Sweden. Johan.Bylund@farmbio.uu.se
Hidestrand
M
M
Ingelman-Sundberg
M
M
Oliw
E H
EH
D001189:Aryl Hydrocarbon Hydroxylases; D003577:Cytochrome P-450 Enzyme System / Q000032:analysis / Q000378:metabolism*; D006801:Humans; D008297:Male; D006899:Mixed Function Oxygenases / Q000378:metabolism*; D011449:Prostaglandin Endoperoxides / Q000378:metabolism*; D012669:Seminal Vesicles / Q000201:enzymology*
D011449:Prostaglandin Endoperoxides; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; D001189:Aryl Hydrocarbon Hydroxylases; C120451:CYP4F8 protein, human; C026961:prostaglandin omega hydroxylases