Isolation of a calcium‐binding protein from an oxygen‐evolving photosystem II preparation

Abstract

Heat treatment of a highly active photosystem II preparation (600 μmol O 2 . mg Chl −1 .h −1 ) caused the release of several polypeptides. One of the polypeptides was found to bind to a fluphenazine‐Sepharose affinity column in a calcium‐dependent manner. The purified polypeptide was able to stimulate calmodulindepleted 3',5'‐cyclic nucleotide phosphodiesterase, indicating a possible similarity with calmodulin.