Some properties of purified fractions from bean etioplast membranes

Distribution of proteins, protochlorophyllide and photoactivity was studied in fractions obtained from bean etioplast membranes purified by linear or discontinuous sucrose density gradient centrifugation. The polypeptide pattern of two selected membrane fractions was examined by means of polyacrylamide gel electrophoresis. Both fractions contained the doublet of molecular weights 34.000-35.000 characteristic of NADPH-Protochlorophyllide oxido-reductase but differed by accompanying proteins. When both fractions were illuminated, protochlorophyllide was photoreduced in chlorophyllide fluorescing at 688 nm. During a subsequent 30 min. dark period, the emission peak shifted rapidly up to 678 nm in one of the fractions while it moved slowly to 683 nm in the other one. The possible occurrence of two phototransformable protochlorophyllide-complexes is discussed. Delta-aminolevulinic acid pretreatment of etiolated leaves led to an increase in the amount of proteins in the etioplast membranes.