A substantial portion of the ribulose 1,5-diphosphate carboxylase activity in the endosperm of germinating castor beans (Ricinus communis var. Hale) is recovered in the proplastid fraction. The partially purified enzyme shows homology with the enzyme from spinach (Spinacia oleracea) leaves, as evidenced by its reaction against antibodies to the native spinach enzyme and to its catalytic subunit...

The well characterized castor bean (Rhscm is L*) allergens were Identdfied as the low molecular weight albmin storae protein In the matrix of the protein bodles in the edsp mThe metbods of Idetifcatdon involved molecular weight estbition, amino acid compositon, stabilty at 1000 C, sobulity In various solvents, gel elec rs , and Immunological technbques. The fdinig explains the wide distrbution ...

Three pathways for phosphatidylcholine synthesis were assayed in castor bean (Ricinus communis var. Hale) endosperm. Phosphatidylethanolamine: S-adenosylmethionine methyl transferase occurred predominantly in the endoplasmic reticulum fraction, but some activity appeared in the mitochondria. Phosphorylcholine glyceride transferase occurred exclusively in the endoplasmic reticulum. The phosphory...

Subceliular organelles from castor bean (Ricuns commnwuis) endosperm were isolated on discontinuous sucrose gradients from germinating seeds which were 1 to 7 days postbit o. Marker enzyme activities of the organeUes were measured (fumarase, catalase, and triose phosphate isomerase) and the homogeneity of the organelle fractions was examined by electron microscopy. Pyrumate dehydrogenase comple...

Phosphatidylethanolamine synthesis by CDP-ethanolamine:1,2-diacylglycerol ethanolaminephosphotransferase (EC 2.7.8.1) from the endoplasmic reticulum of castor bean (Ricinus communis L. var. Hale) endosperm was characterized. The Michaelis-Menten constant of the enzyme for CDP-ethanolamine was approximately 8.0 micromolar. The pH optimum was 6.5 and a divalent cation was an absolute requirement ...

The endosperm of castor bean seeds (Rkinus comunuis L.) contains two -SH-dependent amptidases, one hydrolyzing L-leucine-,Bnaphthylamide optimally at pH 7.0, and the other hydrolyzing L-proline,B-naphthylamide optimally at pH 7.5. After germination the endosprm contains in addition an -SH-dependent hemoglobin protease, a serinedependent carboxypeptidase, and at least two -SH-dependent enzymes h...

Vacuoles were prepared from endosperm tissue of 4-day-old castor bean seedlings (Ricinus communis var. Hale) and purified on a stepped sucrose gradient. It was shown by assays of marker enzymes that there was only trace contamination of the final preparation by other organeiles (mitochondria, glyoxysomes, nuclei, spherosomes, and plastids) and by cytoplasmic components. Hydrolytic enzymes (acid...

Phosphatidylserine synthesis by the endoplasmic reticulum fraction isolated from castor bean (Ricinus communis var. Hale) endosperm was assayed by measuring the incorporation of (14)C-l-serine into chloroform-soluble material. Both phosphatidylserine and phosphatidylethanolamine were identified as products. The incorporation required calcium ions and showed an optimum pH of 7.8 in 2 mm CaCl(2)....