Effect of the three-dimensional structure on the deamidation reaction of ribonuclease A.
Kinetic data on the deamidation reaction of Asn67 in RNase A and of Asn3 in the two peptides Ac-Cys-Lys-Asn-Gly-Gln-Thr-Asn-Cys-NH2 and Ac-Cys(Me)-Lys-Asn-Gly-Gln-Thr-Asn-Cys(Me)-NH2, whose sequences are similar to that of the deamidation site in the enzyme, have been determined in a wide range of pH and buffer concentrations. The values of the observed rate constant (k) for the enzyme are markedly lower than those for the peptides. However, the k dependence on pH and buffers is similar for all three substrates, indicating a similar reaction mechanism. The lower k-values for the enzyme have been quantitatively related to the thermal stability and the three-dimensional structure of the enzyme.
Capasso
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Dipatimento di Scienze Ambientali, Seconda Università di Napoli, Caserta, Centro di Studio di Biocristallografia, CNR, Italy. capasso@chemna.dichi.unina.it
Salvadori
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D000577:Amides / Q000737:chemistry*; D001216:Asparagine / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D015394:Molecular Structure; D010446:Peptide Fragments / Q000737:chemistry; D012259:Ribonuclease, Pancreatic / Q000737:chemistry*; D013388:Succinimides / Q000737:chemistry
D000577:Amides; D010446:Peptide Fragments; D013388:Succinimides; D001216:Asparagine; D012259:Ribonuclease, Pancreatic