Capasso S, Mazzarella L, Sica F, Zagari A
Dipartimento di Chimica, Università di Napoli, Italy.
Pept Res. 1989 Mar-Apr;2(2):195-200.
The deamidation reaction of asparaginyl peptides was studied as a function of the pH and sequence. The deamidation of Boc-Asn-Gly-Gly-NH2 and the hydrolysis of the corresponding aminosuccinyl (Asu) peptide, Boc-Asu-Gly-Gly-NH2, were carried out in the pH ranges 5-10, whereas the deamidation of Boc-Asn-Ala-Gly-NH2, Boc-Asn-Gly-Ala-NH2 and Boc-Asn-Ser-Gly-NH2 was studied at pH 8.9 only. In each case, the conversion of the amide side-chain moiety of the Asn to carboxyl group occurs via a succinimide intermediate (Asu), and its breakdown leads to a normal and an isoaspartyl peptide. The kinetic constants of the Asu formation and the hydrolytic step increase markedly at basic pH. The influence of the side chain of the residue next to Asn is also discussed.
研究了天冬酰胺基肽的脱酰胺反应与pH值和序列的关系。在pH值5 - 10范围内进行了Boc-Asn-Gly-Gly-NH2的脱酰胺反应以及相应的氨基琥珀酰（Asu）肽Boc-Asu-Gly-Gly-NH2的水解反应，而仅在pH 8.9下研究了Boc-Asn-Ala-Gly-NH2、Boc-Asn-Gly-Ala-NH2和Boc-Asn-Ser-Gly-NH2的脱酰胺反应。在每种情况下，天冬酰胺酰胺侧链部分向羧基的转化通过琥珀酰亚胺中间体（Asu）发生，其分解产生正常肽和异天冬酰胺基肽。在碱性pH条件下，Asu形成和水解步骤的动力学常数显著增加。还讨论了紧邻天冬酰胺的残基侧链的影响。
