Premium
Testing the Shifting Specificity Model for Enzyme Catalysis
Author(s) -
Britt Billy Mark
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.502.1
Subject(s) - enzyme , catalysis , chemistry , enzyme catalysis , ground state , stereochemistry , biochemistry , physics , quantum mechanics
The Shifting Specificity model (SSM) for enzyme catalysis explains enzyme catalysis generally and addresses the deficiencies in the Haldane‐Pauling‐Koshland model (HPKM) of enzyme catalysis. The tenets of the SSM are outlined and the results of experiments to test the validity of each model are presented. Strong ground state/enzyme interactions are positively correlated with catalytic efficiency. Larger enzymes are better catalysts than smaller enzymes. These data are explained by the SSM which calls for a direct role for the entire enzyme molecule in the catalytic event. The HPKM has no such role and maintains that weak ground state interactions are favorable for catalysis. Many enzymes have two folded conformations. For bovine adenosine deaminase, the low‐temperature (< 30ºC) conformation appears to be better optimized for interaction with the reaction transition state than does the physiological conformation. The SSM requires two global conformations of the enzyme unlike the HPKM which requires only one. It is argued that the SSM better explains the data than does the HPKM.