Is the manganese stabilizing 33 kDa protein of photosystem II attaining a ‘natively unfolded’ or ‘molten globule’ structure in solution?

Abstract

This study compares the properties of the extrinsic 33 kDa subunit acting as ‘manganese stabilizing protein’ (MSP) of the water oxidizing complex with characteristic features of proteins that are known to attain a ‘natively unfolded’ or a ‘molten globule’ structure. The analysis leads to the conclusion that the MSP in solution is most likely a ‘molten globule’ with well defined compact regions of β structure. The possible role of these structural peculiarities of MSP in solution for its function as important constituent of the WOC is discussed.