Sulfhydryl groups responsible for extreme lability of human cholesterol 7alpha-hydroxylase identified by site-directed mutagenesis.

Cholesterol 7alpha-hydroxylase (cholesterol-NADPH oxidoreductase, EC 1.14.13.

Half-life of cholesterol 7alpha-hydroxylase activity and enzyme mass differ in animals and humans when determined by a monoclonal antibody against human cholesterol 7alpha-hydroxylase.

A monoclonal antibody against human cholesterol 7alpha-hydroxylase was produced, and the half-life of the enzyme was studied. Both the activity and protein mass of the enzyme were measured at timed intervals during microsomal incubation. The enzyme activity dropped rapidly; the half-life was 1, 1.