Purification and characterization of corticosteroid side chain isomerase

Journal Article · Mon Feb 05 23:00:00 EST 1990 · Biochemistry; (USA)

DOI:https://doi.org/10.1021/bi00457a008· OSTI ID:6709441

Marandici, A; Monder, C ^[1]

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1. The Population Council, New York, NY (USA)

Corticosteroid side chain isomerase of rat liver catalyzes the interconversion of the ketol (20-oxo-21-ol) and (20-hydroxy-21-al) forms of the corticosteroid side chain. The enzyme has now been purified to apparent homogeneity from rat liver cytosol by sequential chromatography on anionic, hydroxylapatite, and gel filtration columns. Ketol-aldol isomerization is followed by measuring the exchange of tritium from 21-tritiated steroids with water. The native enzyme is a dimer of MW 44,000. The isoelectric point is 4.8 {plus minus} 0.1 pH units. The purified enzyme is stimulated by Co{sup 3+} or Ni{sup 2+}. The enzyme utilizes 11-deoxycorticosterone, corticosterone, and 17-deoxycortisol as substrate but not cortisol, tetrahydrocortisol, and prednisolone. Tritium-water exchange of (21S)-(21-{sup 3}H)DOC is a pseudo-first-order reaction; 21-{sup 3}H exchange from the 21R isomer proceeds with first-order kinetics only after a lag associated with its epimerization to the 21S form.

• OSTI ID: 6709441
• Journal Information: Biochemistry; (USA), Journal Name: Biochemistry; (USA) Vol. 29:5; ISSN 0006-2960; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ADRENAL HORMONES
ANIMALS
BIOCHEMICAL REACTION KINETICS
BODY
CATALYSIS
CORTICOSTEROIDS
DIGESTIVE SYSTEM
ELECTROPHORESIS
ENZYME ACTIVITY
ENZYMES
GLANDS
HYDROGEN COMPOUNDS
HYDROXY COMPOUNDS
ISOMERASES
KETONES
KINETICS
LIVER
MAMMALS
MICE
MOLECULAR STRUCTURE
ORGANIC COMPOUNDS
ORGANS
PREGNANES
PURIFICATION
RATS
REACTION KINETICS
RODENTS
STEROIDS
TRITIUM COMPOUNDS
VERTEBRATES