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@article{nilsson_substrate_2014,
	title = {Substrate water exchange in photosystem {II} core complexes of the extremophilic red alga \textit{{Cyanidioschyzon} merolae}},
	volume = {1837},
	issn = {0005-2728},
	url = {https://www.sciencedirect.com/science/article/pii/S0005272814001078},
	doi = {10.1016/j.bbabio.2014.04.001},
	abstract = {The binding affinity of the two substrate–water molecules to the water-oxidizing Mn4CaO5 catalyst in photosystem II core complexes of the extremophilic red alga Cyanidioschyzon merolae was studied in the S2 and S3 states by the exchange of bound 16O-substrate against 18O-labeled water. The rate of this exchange was detected via the membrane-inlet mass spectrometric analysis of flash-induced oxygen evolution. For both redox states a fast and slow phase of water-exchange was resolved at the mixed labeled m/z 34 mass peak: kf=52±8s−1 and ks=1.9±0.3s−1 in the S2 state, and kf=42±2s−1 and kslow=1.2±0.3s−1 in S3, respectively. Overall these exchange rates are similar to those observed previously with preparations of other organisms. The most remarkable finding is a significantly slower exchange at the fast substrate–water site in the S2 state, which confirms beyond doubt that both substrate–water molecules are already bound in the S2 state. This leads to a very small change of the affinity for both the fast and the slowly exchanging substrates during the S2→S3 transition. Implications for recent models for water-oxidation are briefly discussed.},
	number = {8},
	urldate = {2024-12-10},
	journal = {Biochimica et Biophysica Acta (BBA) - Bioenergetics},
	author = {Nilsson, Håkan and Krupnik, Tomasz and Kargul, Joanna and Messinger, Johannes},
	month = aug,
	year = {2014},
	keywords = {Membrane-inlet mass spectrometry, Oxygen evolution, Photosystem II, Substrate–water exchange, Water oxidation},
	pages = {1257--1262},
}