In silico prediction of the intrinsic disorder and ligand binding sites of human 3β-hydroxysteroid dehydrogenase type 2 enzyme

In human, the 3β-hydroxysteroid dehydrogenase (HSD3B)/Δ4,5-isomerase is an important enzyme in steroid hormone biosynthesis. It catalyzed the conversion of Δ5-steroid precursors to respective Δ4-ketosteroids. There were two HSD3B isoenzymes designated as type 1(HSD3B1) and type 2 (HSD3B2), encoded by two different genes located in chromosome 1p13.1. The mutations in HSD3B2 gene could lead to congenital adrenal hyperplasia and impaired steroidogenesis in both the adrenals and gonads leading to varieties of phenotypes. It was known that many proteins had intrinsically disordered regions (IDRs) and sometimes the entire protein lacked a stable tertiary structure, known as intrinsically disordered proteins (IDPs). These IDRs were attractive target for potential drug discovery. The HSD3B2 was found to possess several IDRs and the regions of IDRs varied according to the algorithm or server used to predict them. The HSD3B2 was predicted to contain two ligand binding sites for NAD and ATP and a single cavity. Some amino acid residues involved in formation of cavity and ligand binding sites were within the intrinsically disordered regions.