重组黏玉米谷氨酰胺转氨酶的酶学性质及其对乳蛋白的交联作用  

Enzymatic Characterization of Recombinant Zea mays Transglutaminase Expressed in Escherichia coli and Effect of Enzymatic Cross-linking on Milk Proteins

作　　者：李洪波[1] 李金 李红娟[1] 于景华[1] Li Hongbo;Li Jin;Li Hongjuan;Yu Jinghua(School of Food and Engineering and Biological Technology, Tianjin University of Science ＆ Technolog)

机构地区：[1]天津科技大学食品工程与生物技术学院,天津300457

出　　处：《中国食品学报》2018年第1期49-55,共7页Journal of Chinese Institute Of Food Science and Technology

基　　金：国家自然科学基金项目(31601496)

摘　　要：目的:从重组大肠杆菌中分离纯化黏玉米来源的谷氨酰胺转氨酶(TGZ),研究其酶学性质及对乳蛋白的交联作用。方法:采用荧光测定法研究重组TGZ的动力学参数、最适反应温度、温度稳定范围、最适反应p H值、p H稳定范围及金属离子对酶活性的影响,明确该重组酶的酶学性质。以微生物源TGase(MTG)为对照,通过SDS-PAGE分析TGZ对乳蛋白的交联作用。结果 :在p H 8.0,37℃的条件下,重组TGZ的反应动力学常数Km为1.55μmol/L,最大反应速率Vmax为155/min。该酶的最适反应温度为45℃,具有较稳定的耐热性。该酶的最适反应p H值为8.0,具有较强的耐碱性。K+、Ca2+、Na+和Ba2+对该酶的活性具有促进作用,Fe3+、Cu2+和Zn2+的抑制作用较强。对乳中酪蛋白和乳清蛋白的交联作用表明酪蛋白是TGZ的良好底物。结论:重组TGZ的酶学性质为其进一步在相关食品中的应用提供了理论依据。Objective： The Zea mays transglutaminase（TGZ） was purified from recombinant Escherichia coli. The main objective of this study was to characterize this enzyme and to assess its cross-linking effect on the milk protein.Method： The properties of recombinant TGZ, such as kinetic parameters, optimum temperature, thermo stability, optimum pH, pH stability and stability of TGZ against metal ion, were studied by the fluorometric method. The polymerization effect of TGZ on milk protein was analyzed by SDS-PAGE, and microbial transglutaminase（MTG） was used as a control. Result： The recombinant TGZ catalyzed casein with a Michaelis constant of 1.55 μmol/L and a maximum velocity of 155/min at pH 8.0 and 37 ℃. The optimum temperature of TGZ was 45 ℃ and this enzyme was discovered to be relatively thermo-stable. The enzyme showed alkali resistance, and exhibited higher activity at pH 8.0. The activity of TGZ was promoted by K^＋, Ca^2＋, Na^＋ and Ba^2＋, and inhibited by Fe^3＋, Cu^2＋ and Zn^2＋. The cross-linking reaction of TGZ to the casein and whey protein was studied and the result showed that casein was the substrate of TGZ. Conclusion： The characterization of recombinant TGZ provided a theoretical evidence for the future application of plant transglutaminase in food industry.

关 键 词：黏玉米来源谷氨酰胺转氨酶 酶学性质 乳蛋白 交联作用 

分 类 号：TS201.25[轻工技术与工程—食品科学]