Role of electrostatics in antibody-antigen association: anti-hen egg lysozyme/lysozyme complex (HyHEL-5/HEL).
A recently developed multigrid-based Newton method for solving the nonlinear Poisson-Boltzmann equation is applied in an investigation of molecular recognition in the system consisting of the monoclonal antibody HyHEL-5 and hen egg lysozyme. The electrostatic free energy of binding is calculated for the wild-type complex and various mutants in which electrostatic interactions between the two proteins are altered. Mutations which neutralize or reverse the charge of any of the residues involved in salt-links in the native system always yield decreased binding affinities. The stability of the complex can be enhanced through the formation of a new salt-bridge obtained by mutating an asparagine residue of the lysozyme to the negatively-charged aspartate. Ionic strength effects are also examined and found to be significant in some cases.
Slagle
S P
SP
Department of Physiology and Biophysics, Beckman Institute, University of Illinois at Urbana-Champaign 61801.
Kozack
R E
RE
Subramaniam
S
S
D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry*; D000936:Antigen-Antibody Complex; D001665:Binding Sites; D001666:Binding Sites, Antibody; D002645:Chickens; D004563:Electrochemistry; D005260:Female; D008958:Models, Molecular; D009113:Muramidase / Q000737:chemistry* / Q000276:immunology*; D009994:Osmolar Concentration; D017433:Protein Structure, Secondary; D013816:Thermodynamics
D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex; D009113:Muramidase