Isolation of an Mn‐carrying 33‐kDa protein from an oxygen‐evolving photosystem‐II preparation by phase partitioning with butanol

Abstract

An Mn‐containing 33‐kDa protein was isolated by phase partitioning with 50% n ‐butanol from an O 2 ‐evolving photosystem‐II preparation. The Mn content in the 33‐kDa protein increased when 1 mM potassium ferricyanide and 0.4 mM diaminodurene were present as oxidants during the butanol treatment and the following dialysis. Under these conditions, 0.1–0.25 atom Mn was detected in one 33‐kDa protein molecule. EPR spectra of the Mn protein showed that the Mn atoms were bound to the protein.