Effect of attaching hydrophilic oligopeptides to the C-terminus of organic solvent-tolerant metal-free bromoperoxidase BPO-A1 from Streptomyces aureofaciens on organic solvent-stability

Metal-free bromoperoxidase BPO-A1 from Streptomyces aureofacience was selected among several similar enzymes exhibiting brominating activity as the most stable haloperoxidase against 70%(v/v) methanol. A comparison of the BPO-A1 and octahistidine-tagged BPO-A1 at the C-terminus (BPO-A1-His8) revealed that the His-tag enhanced the organic solvent-stability of BPO-A1 with pH- and heat-stabilities. Additionally, the contribution of the hydrophilicity at the C-terminal of BPO-A1 to the organic solvent-stability was confirmed employing several mutants bearing hydrophilic oligopeptides. Fortunately, two excellent mutants, BPO-A1-Lys8 and BPO-A1-Arg8, with high stabilities against various water-miscible organic solvents were obtained. In conclusion, the enhancing effect of the hydrophilic oligopeptides on the organic solvent-stability was associated with a decrease in the hydrophobic surface area near the C-terminus. •BPO-A1-His8 selected among several similar enzymes exhibiting brominating activity as the most stable haloperoxidase.•Enhancing effect of a His-tag and other hydrophilic oligopeptides on the organic solvent-stability.•Contribution of C-terminal hydrophilic oligopeptide to hydrophobic core on enzyme surface in the organic solvent-stability.