Enzymatic Synthesis of Cystathionine by Microbial Enzymes

微生物酶酶法合成胱硫醚

基本信息

批准号：
60470132
负责人：
YAMADA Hideaki
金额：
$ 3.33万
依托单位：
Kyoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1985
资助国家：
日本
起止时间：
1985 至 1986
项目状态：
已结题

项目摘要

L-Cystathionine is an important intermediate in transsulfuration in a living thinsg. As it has two asymmetric carbons in the molecule, it is not easy to synthesize L-cystathionine chemically. In addition, L-cystathionine is very expensive amino acid at present. L-Cystathionine is markedly deficient in the brains of untreated homocystinuric patients and fetal brains. Thus, it is meaningful to establish the simple and economical ways of synthesizing L-cystathionine for use in future medical research. We, therefore, investigated enzymatic synthesis of L-cystathionine using microbial cystathionine <gamma> -lyase and cystathionine <gamma> -synthase.Cystathionine <gamma> -lyase occurring in Streptomyces phaeochromogenes can catalyze the <gamma> -replacement reaction of L-homoserine in the presence of L-cysteine to form L-cystathionine. Optimal reaction conditions for the enzymatic synthesis of L-cystathionine were examined. Since concentrations of greater than 10 mM L-cysteine inhibit the <g … More amma> -replacement reaction, it is necessary to keep the concentration of L-cysteine around 10 mM for a high yield of L-cystathionine. Under optimal reaction conditions, defined as the conditions producing the highest yield, cystathionine (3 g) was synthesized enzymatically in 1L of reaction mixture. O-Succinyl-L-homoserine and DL-vinylglycine were better substrates than L-homoserine. Under the optimal conditions, L-cystathionine (11 g/L) was synthesized from O-succinyl-L- homoserine with a substrate conversion ratio of 100%. Next, the reaction conditions for the enzymatic production of L-cystathionine were optimized, using cystathionine <gamma> -synthase, which is abundant in the cells of Erwinia carotovora and Bacillus sphaericus. Under optimal conditions, L-cystathionine (41g/L) was synthesized with conversion ratio of about 90% with the Erwinia and Bacillus enzymes.It can be concluded that cystathionine <gamma> -synthase is more promising and suitable for the enzymatic production of L-cystathionine than cystathionine <gamma> -lyase based on the following reasons;(1) Cystathionine <gamma> -synthase does not catalyze the degradation reaction of L-cystathionine formed.(2) Cystathionine <gamma> -synthase is not sensitive to the allosteric inhibitor , L-cysteine.(3) Specific activity of cystathionine <gamma> -synthase is much higher than cystathionine <gamma> -lyase.In addition, it was also possible to synthesize various kinds of L-homocysteine related amino acids using the cystathionine <gamma> -lyase and cystathionine <gamma> -synthase. Less

l-囊这汀是活体中过渡性的重要中间体。由于该分子中有两个不对称的碳，因此化学合成L-胃静脉并不容易。此外，目前L-囊这汀是非常昂贵的氨基酸。 l-胞汀在未治疗的同囊患者和胎儿大脑的大脑中明显缺乏。这是有意义的，建立合成l-胃静脉的简单和经济方式用于未来的医学研究。 We, therefore, investigated enzymatic synthesis of L-cystathionine using microbial cystathionine <gamma> -lyase and cystathionine <gamma> -synthase.Cystathionine <gamma> -lyase occurring in Streptomyces phaeochromogenes can catalyze the <gamma> -replacement reaction of L-homoserine in the presence of L-cysteine to form l-cystathionine。检查了l-囊这汀的酶促合成的最佳反应条件。由于大于10 mM L-半胱氨酸的浓度抑制了<g…更多的amma>替代反应，因此有必要将L-半胱氨酸的浓度保持在10 mm左右，以高产量L- cystathionine。在最佳反应条件下，定义为产生最高产量的条件，在1L反应混合物中酶促合成胱胺氨酸（3 g）。 o-核辛基-L-霍斯氨酸和DL-乙烯基甘氨酸比L-联合氨酸更好。在最佳条件下，从O-核酸-L-同氨酸的O-链霉菌（11 g/L）合成，底物转化率为100％。接下来，使用Cystathionine <Gamma> - 合成酶优化了酶产生L-环胱巩碱的反应条件，该蛋白在Carotovora和sphaericus的Erwinia carotovora细胞中很丰富。在最佳条件下，合成L-链霉菌（41g/L），转化率与Erwinia和Bacillus酶约为90％。可以得出结论，胱硫醚<gamma> - 伴侣> - 伴奏比cymatathionine <gamma> -synthane更为有障碍，而不是cystathionine <cymatathionine <gammaine <gamma，均为（gammatathine）<gammaine <gamma。半胱硫氨酸<gamma> - 联合不会催化形成的l-胱磷酸蛋白酶的降解反应。（2）胱硫硫氨酸<gamma> - 联合酶对变构抑制剂L- cysteine不敏感。也可以使用胱硫醚<gamma> lyase和cystathionine <gamma> - 伴侣酶合成各种L-联合半胱氨酸相关的氨基酸。较少的