Department of Food Science, Fu Jen Catholic University, Xin Zhuang, Taipei 242, Taiwan.
J Dairy Sci. 2012 Feb;95(2):580-9. doi: 10.3168/jds.2011-4773.
Microbial transglutaminase (MTGase)-induced polymerization of individual milk proteins during incubation was investigated using a proteomics-based approach. The addition of MTGase (0.25-2.0 units/mL) caused the milk proteins to polymerize after a 3-h incubation period. Sodium dodecyl sulfate-PAGE analysis showed that the total intensities of the protein bands that corresponded to α(S)-casein, β-casein, and κ-casein decreased from 8,245.6, 6,677.2, and 586.6 arbitrary units to 1,911.7, 0.0, and 66.2 arbitrary units, respectively. Components with higher molecular weights were observed, and the intensity of these proteins increased after 3h of incubation. These results support that inter- or intramolecular crosslinking occurred in the casein proteins of MTGase-treated milk. Two-dimensional electrophoresis analysis indicated that isomers of β-casein, κ-casein, a fraction of serum albumin, α(S1)-casein, α(S2)-casein, β-lactoglobulin, and α-lactalbumin in the milk were polymerized following incubation with MTGase. In addition, MTGase-induced polymerization occurred earlier for β-casein and κ-casein isomers than for other milk proteins.
采用基于蛋白质组学的方法研究了微生物转谷氨酰胺酶（MTGase）在孵育过程中诱导个体乳蛋白聚合的情况。添加 MTGase（0.25-2.0 单位/毫升）后，牛奶蛋白在 3 小时孵育期后发生聚合。十二烷基硫酸钠-聚丙烯酰胺凝胶电泳分析表明，与 α(S)-酪蛋白、β-酪蛋白和 κ-酪蛋白相对应的蛋白条带的总强度分别从 8245.6、6677.2 和 586.6 个任意单位降至 1911.7、0.0 和 66.2 个任意单位。观察到了具有更高分子量的组分，并且这些蛋白质的强度在孵育 3 小时后增加。这些结果表明 MTGase 处理的牛奶中的酪蛋白蛋白之间或内部发生了交联。二维电泳分析表明，β-酪蛋白、κ-酪蛋白、血清白蛋白的一部分、α(S1)-酪蛋白、α(S2)-酪蛋白、β-乳球蛋白和乳白蛋白的异构体在与 MTGase 孵育后发生聚合。此外，β-酪蛋白和 κ-酪蛋白异构体的 MTGase 诱导聚合比其他乳蛋白更早发生。
