Estrogen synthetase (aromatase). The cytochrome P-450 component of the human placental enzyme is a glycoprotein.
Estrogen synthetase (aromatase) is a cytochrome P-450 enzyme system which converts androgens to estrogens. Although this enzyme has been purified and the cDNA-derived amino acid sequence elucidated, very little is known regarding post-translational modifications of this physiologically crucial enzyme. We show here that the cytochrome P-450 component, P-450ES, purified from human term placental microsomes, is a glycoprotein based on the following evidence: its molecular weight is decreased following treatment with endoglycosidase F, concanavalin A-biotin specifically binds to this protein immobilized on nitrocellulose, and its oligosaccharide composition is consistent with a single N-linked fucosylated complex type carbohydrate chain. In a reconstitution system, the aromatase activity using the endoglycosidase F-treated P-450ES was reduced by about 35-40% relative to the native form, regardless of whether androstenedione or testosterone was used as substrate.
Sethumadhavan
K
K
Department of Biological Sciences, State University of New York, Buffalo 14260.
Bellino
F L
FL
Thotakura
N R
NR
D000735:Androstenedione / Q000378:metabolism; D001141:Aromatase / Q000737:chemistry*; D002241:Carbohydrates / Q000032:analysis; D003208:Concanavalin A / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000302:isolation & purification* / Q000378:metabolism; D005260:Female; D006023:Glycoproteins / Q000302:isolation & purification* / Q000378:metabolism; D006031:Glycosylation; D006801:Humans; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase / Q000378:metabolism; D008970:Molecular Weight; D010920:Placenta / Q000201:enzymology*; D011247:Pregnancy; D011499:Protein Processing, Post-Translational; D013379:Substrate Specificity; D013739:Testosterone / Q000378:metabolism
D002241:Carbohydrates; D006023:Glycoproteins; D003208:Concanavalin A; D013739:Testosterone; D000735:Androstenedione; D003577:Cytochrome P-450 Enzyme System; D001141:Aromatase; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase