氨基酰化酶（N－acylamino－acidamidohydrolase或acylaseⅠ，EC3．5．1．14）是专一水解N-酰基化L-氨基酸的蛋白酶．从水稻黄化苗得到的抽提液，经过硫酸铵分级沉淀、丙酮分级沉淀和阴离子交换层析三个步骤，纯化得到了该酶，比活达到100U／mg蛋白，在无还原剂存在的SDS-聚丙烯酰胺凝胶电泳上显单一条带，分子量为40kD．而凝胶层析分析表明活性分子的分子量约90kD，因此可推测它的活性分子由两个亚基通过非共价键作用组合而成．进一步研究此酶的性质，在所测的五种乙酰化氨基酸中，最适底物为N-乙酰-L-甲硫氨酸．该酶的最适温度为50℃，最适pH为7．0～8．0．Co2＋和Zn2＋能增强酶活性，但烷基化试剂对酶活性没有影响，表明酶活性中心不含活化的巯基或羟基基因

Rice Seedling exhibits high activity of N-acylamino acid amidohydrolase or acylase Ⅰ(EC 3. 5. 1. 14), which can specifically hydrolyzes the acetyl group from N-acetyl-L-amino acid.This enzyme was purified via three steps including ammonium sulfate fractionation, acetone fractionation and DEAE anion exchange chromatography. The purified protein showed a single bandon SDS-polyacrylamide gel electrophoresis with a Mr of 40 kD in the absence of 2-mercaptoethanoland a specific activity of 100 U/mg. The molecular weight determined by HPLC gel filtrationchromatography was around 90 kD, indicating that the active form of acylase Ⅰ is composed oftwo identical subunits linked by noncovalent bonds. Of the five acetylated amino acids tested, Nacetylmethionine was the most favored substrate. The optimal pH and temperature for the enzymatic activity were 7. 0～8 .0 and 50℃, respectively. Metal ions was necessary for its activity.Alkylation reagents did not show any influence on enzymatic activity, implying that the active center of this acylase Ⅰ does not contain any activated thiol or hydroxyl gruop.