摘要
从生姜中分离得到具有凝乳活力的生姜蛋白酶,采用Urea SDS-PAGE、RP-HPLC和MALDI-TOF/MS等方法分析生姜蛋白酶对酪蛋白单体和脱脂乳中酪蛋白的水解作用。结果表明,生姜蛋白酶水解κ-酪蛋白生成的主要产物比较稳定,不会被进一步水解。温度高于60℃时生成κ-CN(f 1-90)和κ-CN(f 1-102)两个末端疏水性肽段,其次为κ-CN(f 1-121),温度较低时,还生成大量分子量高于κ-CN(f 1-121)的产物。在脱脂乳体系中,生姜蛋白酶水解脱脂乳的κ-酪蛋白,而对αS1-、αS2-和β-酪蛋白没有显著的水解作用。主要裂解κ-酪蛋白的Thr121-Ile122键,生成疏水性N末端肽段κ-CN(f 1-121)。这一结果表明生姜蛋白酶凝乳的主要机理是水解κ-酪蛋白Thr121-Ile122肽键,破坏了酪蛋白微粒的稳定性,促使酪蛋白形成凝胶。
Worldwidely, substitution of plant chymosin for calf rennet has always been the hot topic of dairy sci- ence. Ginger protease with milk coagulating activity was isolated from ginger root. The hydrolysis of casein isolates and casein in skim milk was analyzed by Urea SDS-PAGE, RP-HPLC, and MALDI-TOF/MS. The results showed that the primary hydrolyzates of K-casein proteolyzed by ginger protease were stable, and didn＇t undergo further proteoly- sis. At temperatures higher than 60~C , the main products were two N terminal hydrophobie peptides K-CN （f 1-90） and K-CN （f 1-102） with K-CN （f 1-121） to a lesser amount. While at low temperatures, large amount of peptides with molecular weights higher than that of K-CN （f 1-121 ） were formed. Ginger exhibited proteolysis on K-casein, but didn＇ t show significant hydrolysis on as1-, as2-, and β-casein in skim milk system. Proteolysis of K-casein occurred at Thr121-Ile122, and generated a hydrophobic N terminal peptide K-CN （f 1-121 ）. The milk coagulating mechanism of ginger protease was demonstrated to be that the K-casein was hydrolyzed at peptide bond of Thr121-Ile122, which destroyed the stability of casein micelle and formed gels.
出处
《食品与发酵工业》
CAS
CSCD
北大核心
2014年第2期60-65,共6页
Food and Fermentation Industries
基金
辽宁省食品安全重点实验室开放课题项目(LNSAKF2013017)
关键词
生姜蛋白酶
酶学性质
凝乳机理
ginger protease, curd process, milk coagulating mechanism
