Ppsa and tkta are the key genes in central metabolism of aromatic amino acids biosynthesis . ppsa encoding phosphoenolpyrucate synthetase a ( ppsa ) which catalyzes pyruvate into pep ; tkta encoding transketolase a which plays a major role in erythrose - 4 - phosphate ( e4p ) production of pentose pathway Ppsa基因编码磷酸烯醇式丙酮酸合成酶a ( ppsa ) ，该酶催化丙酮酸合成磷酸烯醇式丙酮酸； tkta基因编码转酮酶a ，该酶在磷酸戊糖途径中生成4 -磷酸赤藓糖起主要作用。
