Assignment of the slowly exchanging substrate water of nature's water-splitting cofactor.

ABSTRACT: Identifying the two substrate water sites of nature's water-splitting cofactor (Mn₄CaO₅ cluster) provides important information toward resolving the mechanism of O-O bond formation in Photosystem II (PSII). To this end, we have performed parallel substrate water exchange experiments in the S₁ state of native Ca-PSII and biosynthetically substituted Sr-PSII employing Time-Resolved Membrane Inlet Mass Spectrometry (TR-MIMS) and a Time-Resolved ¹⁷O-Electron-electron Double resonance detected NMR (TR-¹⁷O-EDNMR) approach. TR-MIMS resolves the kinetics for incorporation of the oxygen-isotope label into the substrate sites after addition of H₂¹⁸O to the medium, while the magnetic resonance technique allows, in principle,

SUBMITTER: de Lichtenberg C 

PROVIDER: S-EPMC10945779 | biostudies-literature | 2024 Mar

REPOSITORIES: biostudies-literature