Subunit studies of coupling factor 1 of bean chloroplasts

Abstract

A bean chloroplast coupling factor (CF1) with latent Ca2+-dependent ATPase activity was studied. Immunodiffusion of bean (Phaseolus vulgaris) chloroplast and etioplast coupling factors and spinach coupling factor against antiserum to spinach coupling factor showed partial identity of the bean coupling with that of spinach. An immunoelectrophoretic comparison, under dissociating conditions, of bean leaf extracts and spinach extracts containing CF1 subunits (as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis) gave identical results for both extracts. At least 6 distinct polypeptide species were found. The major species had MW of 42,000, 59,000 and 63,000 daltons. Amino acid analysis of electrophoretically purified bean CF1 gave results similar to those published for spinach CF1.