DAHP synthase, aromatic amino acid synthesis

Of the enzymes associated with aromatic amino acid biosynthesis, there is good evidence that unique isozymes of DAHP (Rubin and Jensen, 1985), chorismate synthetase (d Amato et al 1984), and anthranilate synthase (Brotherton et ai, 1986) are differentially localized within chloroplasts and in the cytoplasm. The regulatory properties of the plastid isozymes are consistent with their involvement in amino acid synthesis. Many of the remaining pathway enzymes have also been detected in plastids, including all those required for the synthesis of EPSP [(1) to (6)] (Mousdale and Coggins, 1985). These results, combined with those obtained during measurements of the biosynthetic capabilities of isolated chloroplasts (Bickel and Schultz, 1979 Buchholz and Schultz, 1980 Schulze-Siebert et ai, 1984), leave little doubt that these organelles are a primary site of aromatic amino acid biosynthesis. 

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