A simple method for oriented immobilization of HydSL hydrogenase of Thiocapsa bogorovii on carbon electrodes

Abstract

HydSL hydrogenase from Thiocapsa bogorovii BBS (formerly Thiocapsa roseopersicina BBS) is NiFe hydrogenase belonging to 1e subgroup. Recently it was shown that C-terminal domain of HydS subunit is important for hydrogenase docking to transmembrane protein Isp1 for electron transfer (https://doi.org/10.1016/j.bbabio.2021.148492.) It is suggested that this C-domain is a hydrophobic transmembrane alpha helix located near distal FeS claster. Using this peculiarity, a simple method for oriented HydSL hydrogenase immobilization on a hydrophobic carbon electrode is developed. The method is based on the incubation of the hydrogenase with carbon paper Freudenberg H24C3 or Vulcan nanoparticles in the solution of MOPS buffer and isopropanol alcohol with ratio 1/2 (v/v) with slow (15 h) evaporation of the solution in humidified atmosphere. The developed electrodes were applied to the fuel cell with Pt catalyst as the oxygen electrode and produced 2 mW cm−2 power with current at this power more than 6 mA cm−2. Furthermore, the fuel cell was stable after 49 days of incubation under the air atmosphere with periodic measurements with some power and current increase.