d-Glyceraldehyde 3-Phosphate Dehydrogenases of Higher Plants

Abstract

A bstract. The D-glyceraldehyde 3-P dehydrogenases of spinaoh leaf, pea seed, and pea shoot were purified. The NADP 'and NAD-linked enzymes of either spinach leaves and pea shoots could not be separated. Changes in the ratio of NADP-to NAD-linked activity oif the spinach leaf and pea shoot enzymes were observed during both purification and stonage of crude extracts. The spinach leaf, pea shoot, and pea seed enzymes differ electrophoretically from each other and from the rabbit muscle enzyme.The The occurrence and distribution of the NAD and NADP-linked glyceraldehyde 3-P dehydrogenases inl higher planits has been investigated in many laboratories. In higher plants the NADP-linked activity was found to occur only in the photosynthetic tissue (10,15). On the other hand, the NAD-linked activity was present in non-chlorophyllous as wvell as chlorophyll containing tissues (12,15

Comparative Enzymology of the Glyceraldehyde 3-Phosphate Dehydrogenases from Pisum sativum

“…The seed enzyme has a low affinity for the oxidized pyridine nucleotide which is surprising considering its probable role in glycolysis. However, these constants might be indicative, as Schulman and Gibbs (26) have suggested, of adaptation to the dessicated storage conditions of the seed and some unique requirements of germination. The kinetic characteristics of the nonphosphaterequiring, irreversible, cytoplasmic glyceraldehyde-3-P dehydrogenase listed in Table VII are those most suitable for its proposed role in the transfer of reducing equivalents from the chloroplast to the cytoplasm (18).…”

“…Pupillo and Piccari (25) could affect the formation of 140,000 mol wt "protomers" of the spinach chloroplast enzyme by NADP. It is possible that the pea enzyme, which as purified contains bound NADP (26), is "locked" in the 140,000 mol wt form and that the spinach enzyme as purified loses bound NADP resulting in aggregation.…”

“…The NAD-and NADP-dependent glyceraldehyde-3-P dehydrogenase activities were assayed in both the oxidative and reductive directions. The reductive assay was performed according to the method of Wu and Racker (30) as described by Schulman and Gibbs (26), except that tris was substituted for sodium pyrophosphate. The oxidative assay was performed according to the procedure of Cori et al (8) as described by Schulman and Gibbs (26).…”

“…The reductive assay was performed according to the method of Wu and Racker (30) as described by Schulman and Gibbs (26), except that tris was substituted for sodium pyrophosphate. The oxidative assay was performed according to the procedure of Cori et al (8) as described by Schulman and Gibbs (26). A unit of activity is defined as the amount of enzyme reducing or oxidizing 1 micromole of pyridine nucleotide per hour at 25 C.…”

Glyceraldehyde 3-Phosphate Dehydrogenases and Glyoxylate Reductase

“…In later investigations, attempts to completely separate NAD-and NADP-dependent activities were unsuccessful (24,34). In fact, Yonushot et al (39) report to have isolated from green spinach leaves a single GPD protein which functions with both NADP and NAD.…”