Studies on chlorophyll formation in Chlorella protothecoides II. Enhancing effects of light and suppressive effects of glucose on the development of porphyrin-synthesizing activity during light-induced greening of etiolated algal cells

Frozen and thawed cells, as well as sonicated cell preparationsof Chlorella protothecoides, were assayed for activity to synthesizeporphyrins from added ALA or PBG. Activity was very low in etiolatedcells, and markedly developed during the process of light-inducedgreening. The development of activity was strongly suppressedby glucose. Activity for the synthesis of URO(gen) from ALAwas initially developed, then the formation of COPRO(gen)-synthesizingactivity ensued. In glucose-suppressed cells as in cells incubatedin continuous darkness, URO was the main porphyrin producedand COPRO was virtually missing in the reaction products withadded ALA, indicating that development of activity for the conversionof URO(gen) to COPRO(gen) is greatly enhanced by light and isrepressed by added glucose. Suppressive effects of CP and CHon the development of porphyrin-synthesizing activity were alsostudied. From these and other results, a tentative scheme ispresented for the enhancing effects of light and the suppressiveeffects of glucose on the development of porphyrin-synthesizingactivity in etiolated algal cells, in correlation with the effectson other processes of chlorophyll biosynthesis. ¹ Present address: National Food Research Institute, Ministryof Agriculture and Forestry, Koto-ku, Tokyo 135, Japan. (Received April 6, 1972; )     

Reevaluation of the Subunit Molecular Weights of Soybean 11S Globulin

The acidic and basic subunits are the main constituents of soybean 11S globulin. Each of these two subunits consists of three major polypeptides of similar size. The molecular weights of the acidic and basic subunits have been previously estimated to be 37,000 and 22,000, respectively, by SDS-polyacrylamide gel electrophoresis (Catsimpoolas et al, J. Set Food. Agric., 22, 448 (1971)). Reevaluation of the molecular weights by 6 m guanidine gel chromatography gave the values of 28,000 and 18,000, respectively. These are supported by results of equilibrium sedimentation in the same solvent. The previously reported values seem to have been overestimated, especially for the acidic subunits. The overestimations seem to be related to the high percentage of acidic amino acids, which causes the conformation of the SDS-protein polypeptide complexes of these subunits to deviate from those of proteins usually employed as standards for molecular weight estimations.     

Studies on chlorophyll formation in Chlorella protothecoides III. Effects of chloramphenicol, cycloheximide, and ethionine on chlorophyll formation

Effects of chloramphenicol, cycloheximide, puromycin and ethionineon the light-independent and subsequent light-dependent processesof chlorophyll formation in "glucose-bleached" cells of Chlorellaprotothecoides were studied. These substances, except puromycin,strongly suppressed different phases of chlorophyll formation.Ethionine most strongly suppressed the light-independent phaseand chloramphenicol an early, relatively short process in thelight-dependent phase of chlorophyll formation. Cycloheximideseverely suppressed all phases of chlorophyll formation. Possibleimplications of these results for the biosynthesis of chlorophyllin algal cells are discussed. ¹ Present address: National Food Research Institute, Ministryof Agriculture and Forestry, Koto-ku, Tokyo 135, Japan. ² Laboratory of Entomology, Faculty of Agriculture, TamagawaUniversity, Machida-shi, Tokyo, Japan (Received October 5, 1972; )     

Isolation of a membrane protein from R rubrum chromatophores and its abnormal behavior in SDS-polyacrylamide gel electrophoresis due to a high binding capacity for SDS.

A membrane protein insoluble in water was isolated by gel chromatography in the presence of 0.1% sodium dodecyl sulfate (SDS) from chromatophores of a photosynthetic bacterium, Rhodospirillum rubrum. This is one of the major membrane proteins of the chromatophore. The protein was found to bind about four grams of SDS per gram, a value which is more than twice the amount generally observed with protein polypeptides derived from water-soluble globular proteins. The electrophoretic behavior of the complex between the membrane protein and SDS is abnormal due to this high capacity for binding SDS. Estimation of the molecular weight of this protein by SDS-polyacrylamide gel electrophoresis was thus impossible. Such an anomaly in SDS binding is unlikely to be restricted to the particular membrane protein described in this paper. The possibility of such a deviation from standard behavior in the interaction with SDS should be taken into consideration in studies of other membrane proteins, since SDS is often used both in analytical and preparative procedures.