Kato T, Kikugawa K
Tokyo College of Pharmacy, Japan.
Food Chem Toxicol. 1992 Jul;30(7):617-26. doi: 10.1016/0278-6915(92)90196-r.
Protein and its components in high concentrations similar to those found in the digestive tract effectively scavenged nitrite and thus inhibited the formation of mutagens from nitrite. Various amino acids at 100 mM, bovine serum albumin (BSA) and trypsinized casein at 100 mg/ml effectively decreased the nitrite level of 50 mM-nitrite solution at pH 3 and 37 degrees C. Most, but not all, amino acids can convert nitrite into nitrogen gas; Pro can be converted into non-mutagenic nitrosoproline, CySH to S-nitrosocysteine, Trp to weakly mutagenic nitrosotryptophan and Tyr to non-mutagenic diazotyrosine. BSA was cross-linked, probably owing to the reaction of Tyr and Lys residues. Most amino acids inhibited more than 50% of nitrosodimethylamine formation in the reaction between 200 mM-dimethylamine and 50 mM-nitrite at pH 3 and 37 degrees C; BSA inhibited 50% of nitrosodimethylamine formation, and trypsinized casein, 100%. Most amino acids inhibited more than 50% of p-diazoquinone formation in the reaction between 25 mM-phenol and 100 mM-nitrite at pH 3 and 37 degrees C; BSA inhibited 80%, and trypsinized casein, 95% of such formation. Trypsinized casein effectively inhibited the development of the mutagenic effects attributable to the formation of diazobamethan from bamethan and nitrite.
高浓度的蛋白质及其组分，类似于在消化道中发现的那些，能有效清除亚硝酸盐，从而抑制由亚硝酸盐形成诱变剂。100 mM的各种氨基酸、100 mg/ml的牛血清白蛋白（BSA）和胰蛋白酶处理的酪蛋白在pH 3和37℃时能有效降低50 mM亚硝酸盐溶液中的亚硝酸盐水平。大多数（但不是全部）氨基酸能将亚硝酸盐转化为氮气；脯氨酸可转化为无诱变作用的亚硝基脯氨酸，半胱氨酸转化为亚硝基半胱氨酸，色氨酸转化为弱诱变的亚硝基色氨酸，酪氨酸转化为无诱变作用的重氮酪氨酸。BSA发生了交联，可能是由于酪氨酸和赖氨酸残基的反应。在pH 3和37℃下，200 mM二甲胺与50 mM亚硝酸盐的反应中，大多数氨基酸抑制了超过50%的亚硝基二甲胺形成；BSA抑制了50%的亚硝基二甲胺形成，胰蛋白酶处理的酪蛋白抑制了100%。在pH 3和37℃下，25 mM苯酚与100 mM亚硝酸盐的反应中，大多数氨基酸抑制了超过50%的对重氮醌形成；BSA抑制了80%，胰蛋白酶处理的酪蛋白抑制了95%的此类形成。胰蛋白酶处理的酪蛋白有效抑制了由巴美生和亚硝酸盐形成重氮巴美生所导致的诱变作用的发展。
