Nakano Takuo, Ozimek Lech
University of Alberta, Department of Agricultural, Food and Nutritional Science, Edmonton, Alberta, T6G 2P5 Canada..
Recent Pat Food Nutr Agric. 2014;6(1):38-44. doi: 10.2174/2212798406666140131122337.
Sialic acid is a carbohydrate moiety of k-casein glycomacropeptide (GMP), which is a 64 amino acid residue C-terminal sialylated phosphorylated glycopeptide released from k-casein by the action of chymosin during cheese making. GMP lacks aromatic amino acids including phenylalanine, tyrosine, and tryptophan. Because of its unique amino acid composition and various biological activities, GMP is thought to be a potential ingredient for dietetic foods (e.g., a food for PKU patients) and pharmaceuticals. Thus, increased attention has been given to the development of techniques to purify GMP. In this review, techniques of GMP purification described in patents and scientific research papers were introduced. A sialic acid assay is the important method to track GMP isolation and purification processes, for which the thiobarbituric acid reaction with 1-propanol as a chromophore extracting solvent is an inexpensive, practical and specific technique. Sephacryl S-200 gel filtration chromatography, cellulose acetate electrophoresis, and sodium dodecyl sulfate polyacrylamide gel electrophoresis are the major techniques to identify sialic acid specific to GMP. Sephacryl S-200 chromatography and cellulose acetate electrophoresis are also used to detect GMP sialic acid in whey pearmeate and whey added commercial margarine samples. Future research includes development of an economical industrial scale method to produce high purity GMP.
唾液酸是κ-酪蛋白糖巨肽（GMP）的碳水化合物部分，GMP是一种由64个氨基酸残基组成的C末端唾液酸化磷酸化糖肽，在奶酪制作过程中由凝乳酶作用于κ-酪蛋白释放而来。GMP缺乏包括苯丙氨酸、酪氨酸和色氨酸在内的芳香族氨基酸。由于其独特的氨基酸组成和多种生物活性，GMP被认为是营养食品（如苯丙酮尿症患者的食品）和药品的潜在成分。因此，人们对纯化GMP的技术开发给予了更多关注。在这篇综述中，介绍了专利和科研论文中描述的GMP纯化技术。唾液酸测定是跟踪GMP分离和纯化过程的重要方法，其中以1-丙醇作为发色团提取溶剂的硫代巴比妥酸反应是一种廉价、实用且特异的技术。Sephacryl S-200凝胶过滤色谱法、醋酸纤维素电泳法和十二烷基硫酸钠聚丙烯酰胺凝胶电泳法是鉴定GMP特有的唾液酸的主要技术。Sephacryl S-200色谱法和醋酸纤维素电泳法也用于检测乳清渗透物和添加了商业人造黄油样品的乳清中的GMP唾液酸。未来的研究包括开发一种经济的工业规模方法来生产高纯度的GMP。
