Rates of Uncatalyzed Peptide Bond Hydrolysis in Neutral Solution and the Transition State Affinities of Proteases
作者:Anna Radzicka、Richard Wolfenden
DOI:10.1021/ja954077c
日期:1996.1.1
acetylglycylglycine, 600 years for the internal peptide bond of acetylglycylglycine N-methylamide, and 350 years for the dipeptide glycylglycine. These reactions, insensitive to changing pH or ionic strength, appear to represent uncatalyzed attack by water on the peptide bond. Comparison of rate constants indicates very strong binding of the altered substrate in the transition states for the corresponding enzyme reactions
为了评估催化内部和 C 端肽键水解的酶的相对效率,在密封的石英管中在升高的温度下检查相应的非酶反应的速率,产生线性阿伦尼乌斯图。结果表明,在 25 °C 的中性溶液中,乙酰甘氨酰甘氨酸 C 端键的肽键水解半衰期约为 500 年,乙酰甘氨酰甘氨酸 N-甲酰胺的内部肽键的半衰期约为 600 年,而二肽甘氨酰甘氨酸。这些对 pH 值或离子强度变化不敏感的反应似乎代表了水对肽键的未催化攻击。速率常数的比较表明,相应酶反应的过渡态中改变的底物的结合非常强,