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 Co^II–protoporphyrin IX reconstituted myoglobin, Co^II–Mb. The electrocatalyzed reduction of Co^II–Mb proceeds via the formation of a complex between the MP-11 monolayer and Co^II–Mb. The association constant of the complex formed between MP-11 and Co^II–Mb is K_a = 1.6 × 10⁵M^–1. Cross-linking of the complex formed between Co^II–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, k_H/k_D ≈ 2.7, suggesting the insertion of the substrate to a Co^III–H species in the rate-limiting step of the hydrogenation process.