Bilogical Roles on N-Acylamino Acid Releasing-enzyme-especially on the protein myristylation-

为了阐明N-酰基氨基酸释放酶的生物学作用，首先研究了它对乙酰甲硫氨酰氨基酸、从二到五丙氨酸的乙酰丙氨酰肽和具有各种酰基的N-酰基甲硫氨酰丙氨酸的底物特异性，结果发现：1）该酶水解除乙酰-L-甲硫氨酰-L-脯氨酸、-L-天冬氨酸和-D-氨基酸外的所有肽。2)在乙酰化衍生物的寡聚丙氨酸，乙酰基二-和三丙氨酸是最迅速水解的酶。3)该酶更有效地从各种N-酰化肽中除去乙酰基或丙酰氨基酸。作为第二步，尝试确定酶的一级结构。通过用无色杆菌蛋白酶I消化从猪肝的酶产生的几种肽的氨基酸序列被部分测定，并且编码该酶的cDNA的分离现在已经在从猪肝构建的cDNA文库中进行，该文库使用对应于如上部分测定的序列的24-mer核苷酸，Glu-Pro-Glu-Glu-Ala-Ala-Ala-Leu-Tyr作为证明。

To elucidate the biological roles on N-acylamino acid releasing-enzyme, its substrate specificity was at first studied with acetylmethionyl amino acids, acetylalanyl peptides ranging from dithrough penta-alanine, and N-acylmethionylalanine having various acyl groups, and the following results were thus found. 1) The enzyme hydrolyses all the peptides tested except for acetyl-L-methionuyl-L-proline, -L-aspartic acid and -D-amino acids. 2) Among acetylated derivatives of oligoalanine, acetyl di- and trialanine were most rapidly hydrolyzed by the enzyme. 3) The enzyme removes more effectively acetyl or propionyl amino acid from various N-acylated peptides. As the second step, the determination of the primary structure of the enzyme was tried. Amino acid sequences of several peptides generated from the enzyme from pig liver, by digestion with Achromobacter protease I were partially determined, and the isolation of cDNA encoding the enzyme has been now performing in the cDNA library constructed from pig liver using a 24-mer nucleotide corresponding to the sequence partially determined as above, Glu-Pro-Glu-Glu-Ala-Ala-Ala-Leu-Tyr, as a prove.