Abstract
The bile acid sulfate sulfatase (BSS) produced by Pseudomonas testosteroni was purified and characterized. Chromatofocusing behavior and amino acid sequence over twelve amino acid residues from N-terminus of the enzyme indicated that BSS was composed of two isoforms of which molecular weights were 125, 000 and 103, 000. Each isoform was a homodimer of a subunit of which molecular weight was 53, 000 or 51, 000, respectively. The optimum pH was 8.5 and BSS was stable at pH 5. 8-8.0. The thermostability above 32°C was improved by the addition of polyols, such as sorbitol, sucrose, and glycerol. BSS was a Mn2+-dependent enzyme and contained 1-2 atoms of manganese in its own protein molecule. All 3α-sulfate esters of the bile acids routinely appearing in human serum were hydrolyzed by BSS to 3β-hydroxyl iso-compounds corresponding to each bile acid and sulfuric acid. We tentatively named this novel enzyme BSS (bile acid 3α-sulfate sulfohydrolase).
