Glutamine synthesis in germinating castor bean endosperm |
| |
Authors: | Nakayama, Hitoshi Fujii, Michiko Miura, Kazuo |
| |
Affiliation: | Department of Agricultural Chemistry, College of Agriculture, University of Osaka Prefecture Sakai, Osaka 591, Japan |
| |
Abstract: | The pathway of glutamine synthesis in germinating castor beanendosperm was investigated by feeding experiments with (2,3-14C)succinateand by determining enzyme activities related to pyruvate formationand utilization. 14C of (2,3-14C)succinate was rapidly and sequentiallyincorporated into amino acids in the following order: aspartateor alanine, glutamate and glutamine. 14CO2 was slowly released,especially during the early hours of incubation. Fluorocitrateinhibited 14CO2 release while aminooxyacetate stimulated itslightly. Fluorocitrate inhibited the incorporation of 14C intoglutamate and glutamine. Aminooxyacetate inhibited 14C incorporationinto aspartate, alanine, glutamate and glutamine. Glutaminesynthetase activity was detected in a soluble fraction. NAD-malicenzyme activity was detected in mitochondria by sucrose densitygradient centrifugation. Activities of pyruvate decarboxylaseand aldehyde dehydrogenasewere detected. Aldehyde dehydrogenasewas partially purified about 60-fold by ammonium sulfate fractionationand the DEAE-cellulose chromatography. The Km values of theenzyme were 0.71 miu for NAD and 0.43 mM for acetaldehyde. Basedon these results and properties of pyruvate kinase reportedpreviously (9), the metabolism of pyruvate in cytosol and mitochondriawas discussed in connection with glutamine synthesis in germinatingcastor bean endosperm. (Received August 25, 1978; ) |
| |
Keywords: | |
本文献已被 Oxford 等数据库收录! |
|