Gaiaschi A, Beretta B, Poiesi C, Conti A, Giuffrida M G, Galli C L, Restani P
Inst. Pharmacological Sciences, University of Milan, Italy.
J Dairy Sci. 2001 Jan;84(1):60-5. doi: 10.3168/jds.S0022-0302(01)74452-9.
Proteolysis has a critical role in defining the typical organoleptic characteristics of Grana Padano, a well-known Italian cheese. During the ripening process, hydrolysis of beta-casein produces different fragments, the most abundant and widely studied of which are gamma-caseins, three polypeptides containing the HOOC-terminal portion of beta-casein. By sodium dodecyl sulfate-PAGE and a specific anti-beta-casein monoclonal antibody, two beta-casein-derived bands were identified in Grana Padano cheese: betaa and betab. Thanks to the identification of the amino acid sequences, it was shown that: a) betaa contains gamma1-casein [beta-casein (29-209)] and the correlated peptide [beta-casein (30-209)]; b) betab contains gamma2-casein [beta-casein (106-209)] and gamma3-casein [beta-casein (108-209)]. The production of betaa and betab by the three enzymes most involved in cheese proteolysis (pepsin, chymosin, and plasmin) was evaluated by performing in vitro digestions. A significant correlation between abundance of some polypeptides and ripening process was shown.
蛋白水解作用在定义意大利著名奶酪帕达诺干酪的典型感官特性方面起着关键作用。在成熟过程中，β-酪蛋白的水解产生不同的片段，其中最丰富且研究最广泛的是γ-酪蛋白，即三种含有β-酪蛋白HOOC末端部分的多肽。通过十二烷基硫酸钠聚丙烯酰胺凝胶电泳（SDS-PAGE）和一种特异性抗β-酪蛋白单克隆抗体，在帕达诺干酪中鉴定出两条源自β-酪蛋白的条带：βa和βb。通过氨基酸序列鉴定表明：a）βa包含γ1-酪蛋白[β-酪蛋白（29 - 209）]和相关肽段[β-酪蛋白（30 - 209）]；b）βb包含γ2-酪蛋白[β-酪蛋白（106 - 209）]和γ3-酪蛋白[β-酪蛋白（108 - 209）]。通过进行体外消化来评估参与奶酪蛋白水解作用的三种主要酶（胃蛋白酶、凝乳酶和纤溶酶）对βa和βb的产生情况。结果显示一些多肽的丰度与成熟过程之间存在显著相关性。
