Kinetic and thermodynamic control of the relative yield of the deamidation of asparagine and isomerization of aspartic acid residues.

Selective deamidation of Asn67 of RNase A to beta-Asp67 and Asp67 residues at neutral pH initially produces greater amounts of the beta-Asp derivative. As the reaction proceeds the relative concentration of [Asp67]-RNase A increases and, at equilibrium, becomes predominant. Such a discrepancy between the kinetic and thermodynamic control on reaction products is discussed in light of information from X-ray three-dimensional analysis and the lower thermodynamic stability of the beta-Asp derivative relative to the parent enzyme.