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A quantitative secondary structure analysis of the 33 kDa extrinsic polypeptide of photosystem II by FTIR
A Ahmed1, H A Tajmir-Riahi, R Carpentier
1Centre de recherche en photobiophysique, Université du Québec a Trois-Rivières, Canada.
Abstract:
In chloroplast photosystem II, the extrinsic polypeptide of 33 kDa is involved in the stabilization the Mn cluster in charge of water splitting and in the fulfilment of the Ca(2+)-cofactor requirement for oxygen evolution. The conformational analysis of the purified 33 kDa extrinsic polypeptide was carried out using FTIR spectroscopy with its self-deconvolution and second derivative resolution enhancement as well as curve-fitting procedures. The FTIR spectroscopic results showed that the isolated polypeptide is characterized by a major proportion beta-sheet conformation (36%) with 27% alpha-helix, 24% turn, and 13% beta-antiparallel structures.