申请人:ALLELIX INC.
公开号:EP0212972A2
公开(公告)日:1987-03-04
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.
乙酰氨基肉桂酸盐可以利用某些分离出来的阿尔卡利根菌属、假单胞菌属、科里奈杆菌属、布莱维巴氏菌属、芽孢杆菌属和微球菌属的微生物细胞合成的酶,高效率地转化为 L-苯丙氨酸。这些分离菌株的细胞在乙酰氨基肉桂酸存在的情况下生长时,能合成将乙酰氨基肉桂酸转化为 L-苯丙氨酸的酶。在有适量乙酰氨基肉桂酸(ACA)存在的情况下,在多种碳源和氮源上生长的细胞中都能合成这种酶。
在含有葡萄糖、苯丙氨酸、乳酸、丙酮酸、柠檬酸、山梨醇、乙酰胺肉桂酸等碳源和苯丙氨酸、组氨酸、乙酰胺肉桂酸等氮源的培养基中,催化这种转化的酶的合成量最大。在含有乳酸盐、苯丙氨酸和乙酰氨基肉桂酸盐的培养基中,细胞最大限度地合成了一种特殊的渗透酶(转运酶)系统,用于将底物转运到细胞中;一种脱氨酶(脱水),用于将 ACA 转化为乙酸盐、NH4 和苯丙酮酸;一种苯丙氨酸脱氢酶,用于将苯丙酮酸重新转化为 L-苯丙氨酸,以及一些耦合脱氢酶(丙酮酸脱氢酶、乳酸脱氢酶、乙酰氨基肉桂酸盐脱氢酶和乙酰氨基肉桂酸盐脱氢酶)、乳酸脱氢酶),它们再生并提供还原型辅助因子 NADH,以驱动最后的苯丙氨酸合成脱氢酶反应。因此,这些微生物的细胞或提取物含有一个天然耦合的酶系统,能够将乙酰氨基肉桂酸或相关化合物转化为特异性 L-苯丙氨酸或其他相关氨基酸或其衍生物。