Affinity chromatography of 3 alpha-hydroxysteroid dehydrogenase from Pseudomonas testosteroni. Use of N,N-dimethylformamide to prevent hydrophobic interactions between the enzyme and the ligand

Carbonyl Reductases and Pluripotent Hydroxysteroid Dehydrogenases of the Short-chain Dehydrogenase/reductase Superfamily

Carbonyl reduction of aldehydes, ketones, and quinones to their corresponding hydroxy derivatives plays an important role in the phase I metabolism of many endogenous (biogenic aldehydes, steroids, prostaglandins, reactive lipid peroxidation products) and xenobiotic (pharmacologic drugs, carcinogens, toxicants) compounds. Carbonyl-reducing enzymes are grouped into two large protein superfamilies: the aldo-keto reductases (AKR) and the short-chain dehydrogenases/reductases (SDR). Whereas aldehyde reductase and aldose reductase are AKRs, several forms of carbonyl reductase belong to the SDRs. In addition, there exist a variety of pluripotent hydroxysteroid dehydrogenases (HSDs) of both superfamilies that specifically catalyze the oxidoreduction at different positions of the steroid nucleus and also catalyze, rather nonspecifically, the reductive metabolism of a great number of nonsteroidal carbonyl compounds. The present review summarizes recent findings on carbonyl reductases and pluripotent HSDs of the SDR protein superfamily.

Functional and immunological relationships between metyrapone reductase from mouse liver microsomes and 3 alpha-hydroxysteroid dehydrogenase from Pseudomonas testosteroni

3 Alpha-hydroxysteroid dehydrogenase (3 alpha-HSD) from Pseudomonas testosteroni was shown to reduce the xenobiotic carbonyl compound metyrapone (MPON). Reversely, MPON reductase purified from mouse liver microsomes and previously characterized as aldehyde reductase, was competitively inhibited by 3 alpha-HSD steroid substrates. For MPON reduction both enzymes can use either NADH or NADPH as co-substrate. Immunoblot analysis after native and SDS gel electrophoresis of 3 alpha-HSD gave a specific crossreaction with the antibodies against the microsomal mouse liver MPON reductase pointing to structural homologies between these enzymes. In conclusion, there seem to exist structural as well as functional relationships between a mammalian liver aldehyde reductase and prokaryotic 3 alpha-HSD. Moreover, based on the molecular weights and the co-substrate specificities microsomal mouse liver MPON reductase and Pseudomonas 3 alpha-HSD seem to be members of the short-chain alcohol dehydrogenase family.

Purification and characterization of androgen binding protein from the rat epididymis

Androgen binding protein (ABP) was purified from rat epididymides by sequential ammonium sulfate precipitation, affinity chromatography, gel filtration, and DEAE ion exchange chromatography. The column matrix formed by coupling dihydrotestosterone-17 alpha-(hexanoic acidY to agarose via diisopropylamine was stable during the extensive washing required following application of crude tissue extracts to the affinity matrix. In addition, when used under the optimal conditions, the column produced a 1600-fold purified in a single step. Apparent homogeneity of the final product was shown by polyacrylamide gel electrophoresis, sedimentation equilibrium, and constant specific activity across the peak of the final chromatograph. The molecular weight determined by sedimentation equilibrium at pH 7.4 was 85 000. By contrast, the molecular weight determined by sedimentation equilibrium in guanidine.HCl and by sodium dodecyl sulfate-polyacrylamide gel electrophoresis was approximately one-half that of the native protein, suggesting that suggesting that ABP is comprised of subunits.

[Steroid-transforming enzymes from microorganisms. IX. Affinity chromatographic preparation and studies of the apoenzyme from a 4-en-3-oxosteroid: (acceptor)-1-en-oxidoreductase from Nocardia opaca]

From the flavoenzyme, 4-en-3-oxosteroid: (acceptor)-1-en-oxidoreductase of Nocardia opaca, prosthetic group and apoenzyme were separated quantitatively by means of affinity chromatography in the presence of 2 M (NH4)2 at pH 3.0. Subsequently the apoenzyme was eluted from affinity matrix by 0.01 M phosphate buffer, pH 8.0, whereas under these conditions the intact enzyme could not be eluted. The whole enzyme activity applied could be restored by incubation of the eluted apoenzyme with FAD. The binding strength of the apoenzyme to the immobilized steroid ligand is highly decreased in comparison to the native enzyme and can be interpreted by the action of rest hydrophobicity. That indicates the essential character of FAD for both ligand binding and transformation.