Asparagine deamidation: pH-dependent mechanism from density functional theory

Baron Peters, Bernhardt L. Trout

Research output: Contribution to journalArticlepeer-review

Abstract

Asparagine deamidation is a decisive event in chemotherapy-induced apoptosis and a major obstacle in the formulation of monoclonal antibodies. Despite the importance of deamidation, little is known about the elementary reactions involved. B3LYP/6-31+G(d,p)/COSMO-RS calculations were used to obtain stable structures and transition states for a network of reactions. Calculated rate constants were incorporated into a kinetic model of the pH dependence and compared to a pseudo-steady-state model. At low pH, the calculations show that deamidation occurs by direct acid-catalyzed hydrolysis to aspartate. At neutral to basic pH, deamidation proceeds by the initial formation of a tetrahedral intermediate. The intermediate can be converted to succinimide by two pathways and three rate-determining steps that shift in relative importance with pH. The calculated pH-dependent rate constant qualitatively agrees with the experimental pH dependence. The rate-determining transition state structures may help to understand chemotherapy-induced apoptosis and improve protein formulations.

Original languageEnglish (US)
Pages (from-to)5384-5392
Number of pages9
JournalBiochemistry
Volume45
Issue number16
DOIs
StatePublished - Apr 25 2006
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry

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