渗透化K.fragilis细胞水解牛乳中乳糖的研究  

Hydrolysis of lactose in milk by β-D-galactosidase from permeabilized K.fragilis cells

作　　者：焦瑞杰 刘建福[1] 羊艺祖 

机构地区：[1]天津商业大学生物技术与食品科学学院,天津300134

出　　处：《食品科技》2013年第11期45-48,共4页Food Science and Technology

摘　　要：应用渗透化K.fragilis细胞中的β-D-半乳糖苷酶水解牛乳中的乳糖,研究了影响乳糖水解率的因素、乳糖的水解动力学,以及酶的稳定性。结果表明:以牛乳中的乳糖为底物,4℃条件下水解75 min,乳糖的水解率为62.66%。该酶的Km值为3.18 mmol/L,Vmax为3.32μmol/min。乳糖的水解产物(葡萄糖)对K.fragilisβ-D-半乳糖苷酶具有反馈抑制作用,反应体系中存在5%葡萄糖时,对该酶活性的抑制率为36.88%。水解牛乳中乳糖连续使用4个批次后,酶活力仍保持初始酶活力的65%以上。渗透化K.fragilis细胞在低温(4℃)下具有良好的贮存稳定性,贮存14 d,β-D-半乳糖苷酶活力保存为95.64%。Abstract： The lactose in milk was hydrolyzed by β-D-galactosidase from permeabilized k.fragilis cells. The factors affecting the degree of lactose hydrolysis, lactose hydrolysis kinetics and the stability of this enzyme were investigated. The results showed that the percentage of lactose hydrolysis was up to 62.66% after reaction 75 min at 4 ℃. The Km value and Vmax value for k.fragilis β-D-galactosidase was 3.18 mmol/L and 3.32μmol/min, respectively. Glucose as a hydrolysis product exhibited feedback inhibition of k.fragilis β-D-galactosidase, 36.88% of the enzymatic activity was inhibited at 50 mg glucose/ mL. After 4 batches of lactose hydrolysis in milk, enzyme activity retained more than 65% of the initial enzyme activity. β-D-galactosidase from permeabilized k.fragilis cells had good storage stability at low temperature, it preserved 95.64% of initial activity after 14 days storage at 4℃.

关 键 词：渗透化K fragilis细胞 Β-D-半乳糖苷酶 乳糖水解 低乳糖牛乳 

分 类 号：TS201.4[轻工技术与工程—食品科学]