Biotechnological and industrial synthesis of coded amino acids

2 Biotechnological and industrial synthesis of coded amino acids 

Knowledge gained of biosynthetic routes to L-a-amino acids and isolation of the enzymes mediating the steps in these routes has been exploited for the industrial-scale manufacture of most of the coded L-a-amino acids. In some cases, the enzymatic production of near-analogues of the coded L-a-amino acids can also be achieved (Goldberg and Williams, 1991 Rozzell and Wagner, 1992). 

To illustrate the methods, a culture medium that contains indole, pyruvic acid, tyrosine phenollyase and an ammonium salt, as well as the usual buffers and salts, will accumulate L-tryptophan or will produce an indole-substituted L-tryptophan if indole itself is replaced by a substituted indole. L-Dopa formed in a system employing tyrosinase from Aspergillus terreus provides a further example of this approach (Chattopadhyay and Das, 1990). 

For a limited range of amino acids, this approach is increasingly in competition 

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