Immunological distinction between fraction I protein and protochlorophyllide holochrome.

Ribulose 1,5-diphosphate carboxylase (RuDP carboxylase) has been shown to be the major component of the Fraction I protein of leaves (5,6). Protochlorophyllide associated with a protein, i.e. protochlorophyllide holochrome (PCH), has been isolated from etiolated bean leaves (1,9,10); upon illumination in vivo or in vitro it is transformed into chlorophyllide holochrome. Several investigators (1,4, 10) have been unsuccessful in their attempts to separate RuDP carboxylase from PCH and consequently have suggested that the proteins might be identical on the basis of their correspondence with regard to sedimentation velocity, molecular weight and diffusion coefficient.