Hernández-Ledesma Blanca, Ramos Mercedes, Recio Isidra, Amigo Lourdes
Instituto de Fermentaciones Industriales (CSIC), Juan de la Cierva 3, 28006 Madrid, Spain.
J Chromatogr A. 2006 May 26;1116(1-2):31-7. doi: 10.1016/j.chroma.2006.03.006. Epub 2006 Mar 31.
In this study, bovine beta-lactoglobulin A (beta-Lg A) was hydrolysed with thermolysin under non-denaturing and heat-denaturing conditions. The peptides released during hydrolysis were identified by HPLC-MS/MS. A total of 25 peptides were identified in the hydrolysate obtained at 37 degrees C for 5 min. Some of these peptides survived to further proteolysis even at higher incubation temperatures. Furthermore, novel cleavage sites localised in the most buried zones of beta-Lg and available for thermolysin were recognised when the incubation temperature increased in the range between 60 and 80 degrees C. Three new peptides, LDA, LKPTPEGD, and LQKW, appeared after 30 min hydrolysis at these incubation temperatures, but they were not identified in the 30-min hydrolysates obtained at 37 and 50 degrees C. Of special interest was the peptide LQKW, corresponding to the fragment f(58-61) that had been previously described as a potent angiotensin-converting enzyme-inhibitor (IC50 value of 34.7 microM).
在本研究中，牛β-乳球蛋白A（β-Lg A）在非变性和热变性条件下用嗜热菌蛋白酶进行水解。水解过程中释放的肽段通过HPLC-MS/MS进行鉴定。在37℃下孵育5分钟得到的水解产物中总共鉴定出25种肽段。其中一些肽段即使在更高的孵育温度下也能抵抗进一步的蛋白水解。此外，当孵育温度在60至80℃范围内升高时，在β-Lg最隐蔽区域中可被嗜热菌蛋白酶作用的新切割位点被识别。在这些孵育温度下30分钟水解后出现了三种新肽段，即LDA、LKPTPEGD和LQKW，但在37℃和50℃下30分钟的水解产物中未鉴定到它们。特别有趣的是肽段LQKW，它对应于先前被描述为一种有效的血管紧张素转换酶抑制剂（IC50值为34.7 microM）的片段f(58 - 61)。
