Microperoxidase-11 functionalized electrodes: an active monolayer interface for the electrocatalyzed reduction of CoII–protoporphyrin IX reconstituted myoglobin and for the generation of integrated protein electrodes for bioelectrocatalyzed hydrogenation of acetylenes

Abstract

Microperoxidase-11, MP-11, is assembled as a monolayer on an Au electrode. The resulting MP-11 monolayer electrode mediates the electrocatalyzed reduction of CoII–protoporphyrin IX reconstituted myoglobin, CoII–Mb. The electrocatalyzed reduction of CoII–Mb proceeds via the formation of a complex between the MP-11 monolayer and CoII–Mb. The association constant of the complex formed between MP-11 and CoII–Mb is Ka = 1.6 × 105M–1. Cross-linking of the complex formed between CoII–Mb and the MP-11 monolayer with glutaric dialdehyde yields a stable integrated electrocatalytic electrode for the stereospecific hydrogenation of acetylenedicarboxylic acid to maleic acid (current yield is ca. 80%). The electrocatalyzed hydrogenation of acetylenedicarboxylic acid reveals an isotope effect, kH/kD ≈ 2.7, suggesting the insertion of the substrate to a CoIII–H species in the rate-limiting step of the hydrogenation process.