Amino acid activation of 3-phosphoglycerate dehydrogenase from peas

When l-methionine was added to an extract of etiolated pea epicotyls activation of 3-phosphoglycerate dehydrogenase occurred and was complete in 20-30 min. Storage of extracts at 5° led to a loss in the ability of l-methionine to activate the enzyme and after 24 hr storage almost no activation was observed. On the basis of tests with 16 compounds the ability to activate 3-phosphoglycerate dehydrogenase was restricted to l-amino acids with intermediate-length side chains. There appears to be no requirement for a reactive group in the side chain. Gel-filtration showed that the higher levels of 3-phosphoglycerate dehydrogenase activity obtained after treatment with l-methionine are relatively stable. © 1975.