title: A simplified electrostatic model for hydrolase catalysis.
abstract: Toward the development of an electrostatic model for enzyme catalysis, the active site of the enzyme is represented by a cavity whose surface (and beyond) is populated by electric charges as determined by pH and the enzyme's structure. The electric field in the cavity is obtained from electrostatics and a suitable computer program. The key chemical bond in the substrate, at its ends, has partial charges with opposite signs determined from published force-field parameters. The electric field attracts one end of the bond and repels the other, causing bond tension. If that tension exceeds the attractive force between the atoms, the bond breaks; the enzyme is then a successful catalyst. To illustrate this very simple model, based on numerous assumptions, some results are presented for three hydrolases: hen-egg white lysozyme, bovine trypsin and bovine ribonuclease. Attention is given to the effect of pH.
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of California, Berkeley, CA, USA; Department of Chemical Engineering, University of Sao Paulo, Sao Paulo, SP, Brazil. Electronic address: pedro.pessoa@poli.usp.br.
authors.forename: Pedro de Alcantara
authors.initials: Pde A
authors.lastname: Pessoa Filho
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of California, Berkeley, CA, USA.
authors.forename: John M
authors.initials: JM
authors.lastname: Prausnitz
mesh_terms: D000465:Algorithms; D000818:Animals; D002384:Catalysis; D020134:Catalytic Domain; D002417:Cattle; D006863:Hydrogen-Ion Concentration; D006867:Hydrolases / Q000737:chemistry*; D008958:Models, Molecular; D008962:Models, Theoretical; D009113:Muramidase / Q000737:chemistry; D011487:Protein Conformation; D055672:Static Electricity; D014357:Trypsin / Q000737:chemistry
chemical_list: D006867:Hydrolases; C421864:hen egg lysozyme; D009113:Muramidase; D014357:Trypsin
keywords: Enzyme; Hydrolase; Model