Wada Masaru, Takagi Hiroshi
Division of Applied Life Science, Graduate School of Agriculture, Hokkaido University, Kita-9, Nishi-9, Kita-ku, Sapporo, 060-8589, Japan.
Appl Microbiol Biotechnol. 2006 Nov;73(1):48-54. doi: 10.1007/s00253-006-0587-z. Epub 2006 Oct 5.
L-Cysteine is an important amino acid both biologically and commercially. Although most amino acids are commercially produced by fermentation, cysteine is mainly produced by protein hydrolysis. However, synthetic or biotechnological products have been preferred in the market. Biotechnological processes for cysteine production, both enzymatic and fermentative processes, are discussed. Enzymatic process, the asymmetric hydrolysis of DL-2-amino-Delta(2)-thiazoline-4-carboxylic acid to L-cysteine, has been developed and industrialized. The L-cysteine biosynthetic pathways of Escherichia coli and Corynebacterium glutamicum, which are used in many amino acid production processes, are also described. These two bacteria have basically same L-cysteine biosynthetic pathways. L-Cysteine-degrading enzymes and L-cysteine-exporting proteins both in E. coli and C. glutamicum are also described. In conclusion, for the effective fermentative production of L-cysteine directly from glucose, the combination of enhancing biosynthetic activity, weakening the degradation pathway, and exploiting the export system seems to be effective.
L-半胱氨酸在生物学和商业上都是一种重要的氨基酸。尽管大多数氨基酸是通过发酵进行商业生产的，但半胱氨酸主要是通过蛋白质水解来生产的。然而，合成产品或生物技术产品在市场上更受青睐。本文讨论了用于生产半胱氨酸的生物技术方法，包括酶促法和发酵法。酶促法，即将DL-2-氨基-Δ(2)-噻唑啉-4-羧酸不对称水解为L-半胱氨酸，已经得到开发并实现了工业化。本文还描述了在许多氨基酸生产过程中使用的大肠杆菌和谷氨酸棒杆菌的L-半胱氨酸生物合成途径。这两种细菌的L-半胱氨酸生物合成途径基本相同。本文还描述了大肠杆菌和谷氨酸棒杆菌中的L-半胱氨酸降解酶和L-半胱氨酸输出蛋白。总之，为了直接从葡萄糖有效地发酵生产L-半胱氨酸，增强生物合成活性、削弱降解途径和开发输出系统的组合似乎是有效的。
