| 摘要 |
Acetamidocinnamate is efficiently converted in high yield, to L-phenylalanine, using enzymes synthesized by microbial cells of certain isolated strains of the genera Alcaligenes, Pseudomonas, Corynebacterium, Brevibakterium, Bacillus and Micrococcus forms. The cells of these isolates synthesize enzymes capable of transforming acetamidocinnamate to L-phenylalanine, when grown in the presence of acetamidocinnamate. The enzymes are synthesized in cells grown on a wide range of carbon and nitrogen sources, in the presence of a suitable amount of acetamidocinnamate (ACA). The enzymes catalysing this transformation are maximally synthesised in cells grown in medium containing, as carbon source, glucose, phenylalanine, lactate, pyruvate, citrate, sorbitol, acetamidocinnamate and as nitrogen source, phenylalanine, histidine, acetamidocinnamate. In a medium containing lactate, phenylalanine and acetamidocinnamate, the cells maximally synthesise a specific permease (translocase) system for transport of substrate into the cell; a deaminase (dehydrate) enzyme which converts ACA to acetate, NH4/<+> and phenylpyruvate; a phenylalanine dehydrogenase enzyme which reaminates phenylpyruvate to produce L-phenylalanine and a number of coupling dehydrogenases (pyruvate dh., lactate dh.) which regenerate and supply reduced cofactor, NADH, to drive the final phenylalanine-synthesising dehydrogenase reaction. Thus, cells or extracts of these microorganisms contain a naturally-coupled system of enzymes capable of transforming acetamidocinnamic acid, or related compounds, to specifically L-phenylalanine or other related amino acids or derivatives thereof. |
