Specificity of amino acid acylases.
Specificity of amino acid acylases.
复制标题
氨基酸酰化酶的特异性。
DOI：
10.1016/s0021-9258(18)55898-1
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发表时间：
1952
期刊：
影响因子：
--
通讯作者：
J. Greenstein
中科院分区：
文献类型：
--
作者：
S. M. Birnbaum;L. Levintow;R. B. Kingsley;J. Greenstein
The observation that chloroacetyl-m-alanine is asymmetrically hydrolyzed by crude kidney preparations at pH 7 (1) led to the development of a general and simple procedure for the resolution of racemic amino acids (2-12). This procedure was based upon the action of a concentrated enzyme preparation obtained from hog kidney which asymmetrically hydrolyzed most N-acylated racemic amino acids, and which in consequence was designated “acylase.” The enzyme concentrate was obtained by an alcohol fractionation of the homogenate at low temperature, and in most cases represented a 4-to 6-fold concentration in activity against chloroacetyl-m-alanine which was employed as the test substrate. It was further assumed that this concentration in activity held toward all other susceptible acylated amino acids. Despite this modest enrichment in acylase activity, the concentrates were readily applied to the resolution of several amino acids (2-ll), and led to the preparation of enantiomorphs which possessed an optical purity greater than 99.9 per cent (13).* We report in this paper the preparation of a much more active acylase from hog kidney by a simplified procedure involving fractionation with ammonium sulfate and acetone. When this new acylase preparation was tested with a large number of N-acylated amino acids, two new observations were made. The first was that the concentrate hydrolyzed all acylated amino acids studied at a rate roughly 30 times greater than that observed with the crude homogenate, with the exception of acylated aspartic acid. This substance was hydrolyzed at a much slower rate than by the crude homogenate. This suggested that N-acylated aspartic acid was hydrolyzed1 Histidine(6), S-benzylcysteine(6), proline (12), and or-aminocaprylic acid (11) were resolved as the respective racemic amides by amidase preparations from hog kidney. Phenylalanine, tyrosine, and tryptophan were resolved as the respective N-chloroacetyl derivatives by a carboxypeptidase preparation from beef pancreas (4). Acylase I has recently been used to prepare the enantiomorphs of aminophenylacetic, aminocyclohexylacetic, and aminocyclohexylpropionic acids in a state of high, optical purity(Rudman, D., Meister, A., and Greenstein, JP, J. Am. Chem. Sot., in press). The use of the acylases in the resolution of these unnatural amino acids, as in the cases of ethionine and the allostereoisomers of threonine(7) and isoleucine(9), yields at once an identification of the L and D enantiomorphs.
