Swaisgood H E
Department of Food Science, North Carolina State University, Raleigh 27695-7624.
J Dairy Sci. 1993 Oct;76(10):3054-61. doi: 10.3168/jds.S0022-0302(93)77645-6.
Of all food proteins, bovine milk proteins are probably the most well characterized chemically, physically, and genetically. The primary structures are known for most genetic variants of alpha s1-, alpha s2-, beta-, and kappa-caseins, beta-lactoglobulin, and alpha-lactalbumin. Secondary and tertiary structures of the whey proteins have been determined, and secondary structures of the caseins have been predicted from spectral studies. The caseins, although less ordered in structure and more flexible than the typical globular whey proteins, have significant amounts of secondary and, probably, tertiary structure. The amphipathic structure of the caseins is especially noteworthy; thus, these proteins most likely are divided into polar and hydrophobic domains. The presence of anionic phosphoseryl residue clusters in the calcium-sensitive casein polar domains is particularly significant because of their interaction with calcium ions, or calcium salts, or both, and the formation of micelles. Flexibility of casein structures is reflected by their susceptibilities to limited proteolysis, which dramatically changes functionality.
在所有食物蛋白质中，牛乳蛋白质在化学、物理和遗传方面可能是特征描述最为详尽的。αs1-、αs2-、β-和κ-酪蛋白、β-乳球蛋白和α-乳白蛋白的大多数遗传变体的一级结构已为人所知。乳清蛋白的二级和三级结构已被确定，酪蛋白的二级结构已通过光谱研究预测得出。酪蛋白虽然在结构上比典型的球状乳清蛋白更无序、更具柔韧性，但具有大量的二级结构，可能还有三级结构。酪蛋白的两亲结构尤其值得注意；因此，这些蛋白质很可能被分为极性和疏水域。钙敏感酪蛋白极性结构域中阴离子磷酸丝氨酸残基簇的存在尤为重要，因为它们与钙离子或钙盐或两者相互作用，并形成胶束。酪蛋白结构的柔韧性体现在它们对有限蛋白水解的敏感性上，这会显著改变其功能。
