Center for Electrochemical Sciences, Ruhr-Universität Bochum, Bochum, Germany.
Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V, 44227, Dortmund, Germany.
Nat Commun. 2020 Feb 14;11(1):920. doi: 10.1038/s41467-020-14673-7.
Redox-active films were proposed as protective matrices for preventing oxidative deactivation of oxygen-sensitive catalysts such as hydrogenases for their use in fuel cells. However, the theoretical models predict quasi-infinite protection from oxygen and the aerobic half-life for hydrogenase-catalyzed hydrogen oxidation within redox films lasts only about a day. Here, we employ operando confocal microscopy to elucidate the deactivation processes. The hydrogen peroxide generated from incomplete reduction of oxygen induces the decomposition of the redox matrix rather than deactivation of the biocatalyst. We show that efficient dismutation of hydrogen peroxide by iodide extends the aerobic half-life of the catalytic film containing an oxygen-sensitive [NiFe] hydrogenase to over one week, approaching the experimental anaerobic half-life. Altogether, our data support the theory that redox films make the hydrogenases immune against the direct deactivation by oxygen and highlight the importance of suppressing hydrogen peroxide production in order to reach complete protection from oxidative stress.
氧化还原活性膜被提议作为保护基质，以防止氧敏催化剂（如氢化酶）的氧化失活，从而将其用于燃料电池中。然而，理论模型预测其对氧具有近乎无限的保护作用，并且在氧化还原膜内氢化酶催化的氢气氧化的需氧半衰期仅约为一天。在这里，我们采用在位共焦显微镜来阐明失活动力学。氧气不完全还原产生的过氧化氢会导致氧化还原基质的分解，而不是生物催化剂的失活。我们表明，碘化物的有效歧化作用可将包含氧敏[NiFe]氢化酶的催化膜的需氧半衰期延长至一周以上，接近实验性厌氧半衰期。总的来说，我们的数据支持氧化还原膜使氢化酶免受氧直接失活的理论，并强调抑制过氧化氢生成以达到完全抗氧化应激保护的重要性。
