Morgan F, Léonil J, Mollé D, Bouhallab S
Laboratoire de Recherches de Technologie Laitière, INRA, Rennes, France.
Biochem Biophys Res Commun. 1997 Jul 18;236(2):413-7. doi: 10.1006/bbrc.1997.6955.
Lactose reacts nonenzymatically with beta-lactoglobulin (beta-LG), the major whey protein, under mild heat treatment and the formation of the complex may be monitored by mass spectrometry. Using Reverse Phase HPLC coupled with Electrospray Ionization MS (ESI-MS) we have measured the global extent of glycosylation and examined the distribution of lactose among the beta-LG glycoforms. Identification of lactosylated sites by trypsinolysis and Tandem MS indicate that, although the glycosylation reaction was non-specific and potentially involved all the reactive sites (alpha- and epsilon-amino groups), beta-LG appeared to have at least two populations of lysine with the distinct ability to react with lactose. These results underline the structural heterogeneity of beta-LG glycoforms, with respect to the number of lactose linked per molecule and to the binding sites involved, which could affect the biological function of beta-LG.
在温和热处理条件下，乳糖与主要的乳清蛋白β-乳球蛋白（β-LG）发生非酶反应，该复合物的形成可通过质谱法进行监测。使用反相高效液相色谱与电喷雾电离质谱联用技术（ESI-MS），我们测定了糖基化的整体程度，并研究了乳糖在β-LG糖型中的分布。通过胰蛋白酶消化和串联质谱对乳糖化位点的鉴定表明，尽管糖基化反应是非特异性的，可能涉及所有反应位点（α-和ε-氨基），但β-LG似乎至少有两类赖氨酸群体，它们与乳糖反应的能力不同。这些结果强调了β-LG糖型在每个分子连接的乳糖数量以及所涉及的结合位点方面的结构异质性，这可能会影响β-LG的生物学功能。
