Analysis of Isolated PS I Polypeptides for Acid Labile Sulfide
Photosystem I (PS I) core particles prepared from a variety of sources all contain the reaction center protein P700-chlorophyll a-protein 1 and a varying number of low molecular weight polypeptides thought to carry one or more of the PS I associated iron-sulfur centres X, A and B. Functional characterization and mapping of these acceptors still remain an enigma, but very recently we have been succesfull in demonstrating the presence of at least one Fe-S centre (most likely centre X (2)) on P700-chlorophyll a-protein 1 (1). Conclusive identification of other PS I polypeptides as Fe-S proteins has not yet been reported although indirect evidence obtained with spinach PS I preparations points towards polypeptides of molecular weight 8 kDa (3) and 19 kDa (4). This paper reports the results on fractionation of full complement PS-I particles into their constituent polypeptides and analysis of their acid labile sulfide content in an attempt to identify additional polypeptides carrying Fe-S centres.
KeywordsReaction Center Protein Zero Valence Sulfur Constituent Polypeptide Acid Labile Sulfide Preparation Point
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