Inactivation of trypsin inhibitors in foods by amino-carbonyl reaction

蛋白质和还原糖之间的氨基-羰基(A-C)反应在各种加工和储存的食品中进行。类卵粘蛋白是蛋清蛋白的主要成分，大豆中含有两种主要的胰蛋白酶抑制剂，即Kuniz蛋白水解酶抑制剂(KSTI)和Borman-Birk抑制剂(BBI)。它们通过其赖氨酸或精氨酸残基形成稳定的EI复合体来抑制胰酶。1.通过将蛋白糖粉混合物在50ﾟC下放置几周，并通过测定它们的胰酶抑制活性和游离氨基和胍基，研究了鸡蛋卵粘蛋白与葡萄糖的氨基-羰基反应。鸡类卵粘蛋白具有精氨酸反应部位的抑制活性在几天后下降，而鹌鹑类卵粘蛋白具有赖氨酸反应部位的抑制活性立即下降，5天后失去60%以上的活性。2.采用上述方法研究了KSTI和BBI与葡萄糖的A-C反应。含精氨酸反应部位的KSTI的抑制活性在几天后下降，而含有赖氨酸反应部位的BBI在10d后立即下降，没有抑制活性。大豆粉中的大豆胰酶抑制剂可能通过葡萄糖处理而失活，卵粘蛋白和大豆抑制剂中的这些失活曲线分别与其游离基和氨基的减少相一致。

The amino-carbonyl (A-C) reaction between proteins and reducing sugars proceeds in various processed and stored foods. Ovomucoid is a major component of egg white proteins, and soybean contents two major torypsin inhibitors, kuniz protease inhibitor (KSTI) and borman -birk inhibitor (BBI). They inhibits trypsin by forming a stable EI complex through their reactive sites of lysine or arginine residues.1.The amino-carbonyl reaction of chicken and Japanese quail egg ovomucoids with glucose was investigated by keeping the powdered protein sugar mixture at 50ﾟC for a few weeks and by measuring their trypsin inhibitory activity and free amino-and guanidino-groups. The inhibitory activity of chicken ovomucoid with arginine reactive site decreased after time lag for a few days, whereas that of quail ovomucoid with lysine reactive site decreased immediately and more then 60% of the activity was lost after 5 days.2.The A-C reaction of KSTI and BBI with glucose was investigated after the keeping as the above method. The inhibitory activity of KSTI with arginine reactive site decreased after time lag for a few days, whereas that of BBI with lysine reactive site decreased immediately and there were no inhibitory activity after 10 days. It was possible that soybean trypsin inhibitors in soybean flour was inactivated by treatment with glucose.These inactivation profiles in ovomucoids and soybean inhibitors were in good agreement with the decrease in their free guanidino-and amino-groups, respectively.