Some Properties of the Initial Four Enzymes Involved in Shikimic Acid Biosynthesis in Tea Plant

Abstract

The initial four enzymes in shikimic acid biosynthesis, 3-deoxy-D-arabino-heptulosonic acid 7-phosphate synthetase (EC 4. 1. 2. 15), 3-dehydroquinic acid synthetase, 3-dehydro-quinate hydro-lyase (EC 4. 2. 1. 10), and shikimate: NADP oxidoreductase (EC 1. 1. 1. 25), were detected in cell-free extracts of tea plant. No significant difference in the enzyme activities was detected between tea cultivars of low and high flavonoid contents. 3-Dehydroquinic acid synthetase was inhibited by gallic acid, (-)-epicatechin gallate, and (-)-epigallocatechin gallate, but not by L-phenylalaaine, L-tyrosine, L-tryptophan, protocatechuic acid, chlorogenic acid, traps-cinnamic acid, (-)-epicatechin, nor (-)-epigallocatechin. The activities of 3-deoxy-D-arabino-heptulosonic acid 7-phosphate synthetase and 3-dehydroquinate hydro-lyase were not affected by any of the above compounds. 3-Deoxy-D-arabino-heptulosonic acid 7-phosphate synthetase was a particulate-bound enzyme and 3-dehydroquinic acid synthetase was a soluble enzyme in tea plant.