Hydroxysteroid Dehydrogenase

I.U.B.: 1.1.1.50 and 1.1.1.51

C.A.S.: 9028-56-2 and 9015-81-0

3 (or 17) β-hydroxysteroid:NAD(P⁺) oxidoreductase

Enzymatic Reaction (image will open in a new window)

3-α-hydroxysteroid:NAD(P⁺) oxidoreductase

Enzymatic Reaction (image will open in a new window) 

Hydroxysteroid dehydrogenases catalyze the interconversion of hydroxyl and carboxyl groups of steroids. Those from Pseudomonas testosteroni are of two types:

1. 3α-Hydroxysteroid Dehydrogenase (1.1.1.50), (α enzyme):

2. 3β- and 17β-Hydroxysteroid Dehydrogenase:

The enzymes have useful application in the assay of steroids (Hurlock and Talalay 1958; Stempfel and Sidbury 1964; Moore 1972). They have been used for the determination of bile acids in blood (Iwata and Yamasaki 1964; Palmer 1969; Leslie 1969; Murphy et al. 1970; Schwarz et al. 1974).

It should be noted that Worthington supplies two preparations: one from the regular Pseudomonas testosteroni (ATCC 11966) culture which produces both the α and β enzymes, and a second from a mutant strain which produces almost only the α enzyme. By using both, the β-hydroxysteroid can be determined by difference.

Teller and Bongiavanni (1963) reported only slight activity of the mutant strain on epiandrosterone indicating but a trace of the β enzyme. Roe and Kaplan (1969) have investigated the specificities of the mutant and wild type strains, and this reference should be consulted for specific details.

Characteristics of Hydroxysteroid Dehydrogenase from Pseudomonas testosteroni:

3α hydroxysteroid dehydrogenase

Molecular weight:

47,000 (Squire et al. 1964; Skålhegg 1974).

Composition:

Amino acid composition has been reported by Squire et al. (1964).

Isoelectric point:

pH 6.1 (Squire et al. 1964).

Specificity:

α enzyme oxidizes only 3α-hydroxysteroids of the C19, C21, C24 series (Talalay 1963).

Inhibitors:

Heavy metals and sulfhydryl-binding reducing agents (Talalay 1963).

Stability:

The Worthington preparation of a enzyme is stable for 6-12 months when stored at -20°C.

3β (or 17β)-hydroxysteriod dehydrogenase

Molecular weight:

100,000 (Squire et al. 1964).

Composition:

Amino acid composition has been reported by Squire et al. (1964).

Isoelectric point:

pH 6.5 (Squire et al. 1964).

Specificity:

Catalyzes the oxidation of 3β-hydroxysteroids of the C19 and C21 series, 17β-hydroxysteroids of the C18, C19, and C21 series, as well as certain 16β-hydroxysteroids (Talalay 1963).

Inhibitors:

Heavy metals and reducing agents. The oxidation of testosterone is inhibited by 3,17α-estradiol and other 1,3,5-estratriene derivatives (Talalay 1963).

Stability:

The Worthington preparation of mixed α and β enzyme is stable for 6-12 months when stored at -20°C.