3α-Hydroxysteroid dehydrogenase is a key enzyme catalyzing steroid metabolism. Its core function is to reversibly catalyze the oxidation of 3α-hydroxysteroids to 3-oxosteroids, using NAD+ or NADP+ as cofactors. As a protein, its molecular weight and optimal reaction conditions vary depending on the source (e.g., human, rat, or bacterial) and subtype. For example, some human subtypes prefer to use NADPH as a cofactor and exhibit optimal activity in a near-neutral environment with a pH of 6.8–7.4. The purified product is typically a white powder.
