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 ...

A fast and efficient method based on a polyethylene glycol (PEG) 600/(NH₄)₂SO₄ aqueous two-phase system for extracting lectin from Zihua snap-bean (Phaseolus vulgaris) seeds was established. According to a Box-Behnken design (BBD), involving four factors at three levels each subjected to analysis of variance (ANOVA) and response surface analysis, the protein recovery and the purification factor...

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)....