Cobinamide production of hydrogen in a homogeneous aqueous photochemical system, and assembly and photoreduction in a (βα)8 protein.

摘要: Components of a protein-integrated, earth-abundant metal macrocycle catalyst, with the purpose H2 production from aqueous protons under green conditions, are characterized. The cobalt–corrin complex, cobinamide, is demonstrated to produce (4.4 ± 1.8 × 10−3 turnover number per hour) in homogeneous, photosensitizer/sacrificial electron donor system pure water at neutral pH. Turnover proposed be limited by relatively low population gateway cobalt(III) hydride species. A heterolytic mechanism for cobalt(II) proposed. Two essential requirements assembly functional protein–catalyst complex interaction cobinamide (βα)8 TIM barrel protein, EutB, adenosylcobalamin-dependent ethanolamine ammonia lyase Salmonella typhimurium: (1) high-affinity equilibrium binding (dissociation constant 2.1 × 10−7 M) and (2) situ photoreduction cobinamide–protein Co(I) state. Molecular modeling cobinamide–EutB shows that these features arise specific hydrogen-bond apolar interactions protein alkylamide substituents ring corrin, accessibility site solution. results establish as platform design engineering robust metallocatalyst operates conditions uses advantages tunable medium material support.