Zale S E, Klibanov A M
Biochemistry. 1986 Sep 23;25(19):5432-44. doi: 10.1021/bi00367a014.
The mechanism of irreversible thermoinactivation of bovine pancreatic ribonuclease A in the pH range relevant to enzymatic catalysis has been elucidated. At 90 degrees C and pH 4, the enzyme inactivation is caused by hydrolysis of peptide bonds at aspartic acid residues (the main process) and deamidation of asparagine and/or glutamine residues. At 90 degrees C and neutral pH (pH 6 and 8), the enzyme inactivation is caused by a combination of disulfide interchange (the main process), beta-elimination of cystine residues, and deamidation of asparagine and/or glutamine residues. These four processes appear to demarcate the upper limit of thermostability of enzymes.
已阐明了牛胰核糖核酸酶A在与酶催化相关的pH范围内不可逆热失活的机制。在90℃和pH 4条件下，酶失活是由天冬氨酸残基处肽键的水解（主要过程）以及天冬酰胺和/或谷氨酰胺残基的脱酰胺作用引起的。在90℃和中性pH（pH 6和8）条件下，酶失活是由二硫键互换（主要过程）、胱氨酸残基的β-消除以及天冬酰胺和/或谷氨酰胺残基的脱酰胺作用共同引起的。这四个过程似乎划定了酶热稳定性的上限。
