Significant advances have taken place in our knowledge of the enzymes involved in steroid hormone biosynthesis since the last comprehensive review in 1988. Major developments include the cloning, identification, and characterization of multiple isoforms of 3β-hydroxysteroid dehydrogenase, which play a critical role in the biosynthesis of all steroid hormones and 17β-hydroxysteroid dehydrogenase where specific isoforms are essential for the final step in active steroid hormone biosynthesis. Advances have taken place in our understanding of the unique manner that determines tissue-specific expression of P450aromatase through the utilization of alternative promoters. In recent years, evidence has been obtained for the expression of steroidogenic enzymes in the nervous system and in cardiac tissue, indicating that these tissues may be involved in the biosynthesis of steroid hormones acting in an autocrine or paracrine manner. This review presents a detailed description of the enzymes involved in the biosynthe...

https://www.researchgate.net/profile/Dale_Buck_Hales/publication/8144948_Overview_of_steroidogenic_enzymes_in_the_pathway_from_cholesterol_to_active_steroid_hormones/links/02e7e5249ac2529059000000.pdf

Overview of Steroidogenic Enzymes in the Pathway from Cholesterol to Active Steroid Hormones

This article summarizes all experimental facts concerning the cold denaturation of single-domain, multi-domain, and multimeric globular proteins in aqueous solutions with and without urea and guanidine hydrochloride. The facts obtained by various experimental techniques are analyzed thermodynamically and it is shown that the cold denaturation is a general phenomenon caused by the very specific and strongly termperature-dependent interaction of protein nonpolar groups with water. Hydration of these groups, in contrast to expectations, is favorable thermodynamically, i.e., the Gibbs energy of hydration is negative and increases in magnitude at a temperature decrease. As a result, the polypeptide chain, tightly packed in a compact native structure, unfolds at a sufficiently low temperature, exposing internal nonpolar groups to water. The reev-aluation of the hydration effect on the base of direct calorimetric studies of protein denaturation and of transfer of non-polar compounds into water leads to r...

Cold denaturation of proteins.

I. Introduction II. 3β-Hydroxysteroid Dehydrogenase/Ketosteroid Isomerase (3β-HSD/KSI) A. Physiological and pharmacological significance B. Cloning and expression of the 3β-HSD/KSI cDNAs C. Structure, regulation, and tissue-specific expression of the 3β-HSD/KSI genes D. 3β-HSD deficiencies III. 17β-Hydroxysteroid Dehydrogenases A. Physiological and pharmacological significance B. Cloning and expression of the 17β-HSD cDNAs C. Structure, regulation, and tissue-specific expression of the 17β-HSD genes D. 17β-HSD deficiency IV. 11β-Hydroxysteroid Dehydrogenases A. Physiological and pharmacological significance B. Cloning and expression of the 11β-HSD cDNAs C. Structure, regulation, and tissue-specific expression of the 11β-HSD genes D. 11β-HSD deficiency V. 3α-Hydroxysteroid Dehydrogenases A. Physiological and pharmacological significance B. Cloning and expression of the 3α-HSD cDNAs C. Structure, regulation, and tissue-specific expression of the 3α-HSD genes D. 3α-HSD deficiencies VI. 20α-Hydroxysteroid Deh...

Molecular Endocrinology of Hydroxysteroid Dehydrogenases

The thermodynamic mechanism of protein stabilization by trehalose.

From the foregoing considerations, the energy-linked transhydrogenase reaction emerges as a powerful and flexible element in the network of redox and energy interrelationships that integrate mitochondrial and cytosolic metabolism. Its thermodynamic features make it possible for the reaction to respond readily to challenges, either on the side of NADPH utilization or on the side of energy depletion. Yet, the kinetic features are designed to prevent a wasteful input of energy when other sources of reducing equivalents to NADP are available, or to deplete the redox potential of NADPH in other than emergency conditions. By virtue of these characteristics, the energy-linked transhydrogenase can act as an effective buffer system, guarding against an excessive depletion of NADPH, preventing uncontrolled changes in key metabolites associated with NADP-dependent enzymes and calling on the supply of reducing equivalents from NAD-linked substrates only under conditions of high demand for NADPH. At the same time, it can provide an emergency protection against a depletion of energy, especially in situations of anoxia where a supply of reducing equivalents through NADP-linked substrates can be maintained. The flexibility of this design makes it possible that the functions of the energy-linked transhydrogenase vary from one tissue to another and are readily adjustable to different metabolic conditions.

/pdf/physiological-roles-of-nicotinamide-nucleotide-54ktgqwzeh.pdf

Physiological roles of nicotinamide nucleotide transhydrogenase.

Purification of a 17β-Hydroxysteroid Dehydrogenase of Human Placenta and Studies on Its Transhydrogenase Function

http://www.jbc.org/content/237/10/3069.full.pdf

Julia A. Adams

Papers

Purification of a 17β-Hydroxysteroid Dehydrogenase of Human Placenta and Studies on Its Transhydrogenase Function

The steroid specificity of the 17beta-hydroxysteroid dehydrogenase of human placenta.