title: X-ray structural and simulation analysis of a protein mutant: the value of a combined approach.
abstract: The effect of the mutation Arg 96 to His on the stability of bacteriophage T4 lysozyme has been previously studied by calorimetric experiments, X-ray crystallography, and free energy simulation techniques. The experimental and calculated values for the difference between the free energy of denaturation of the mutant and the wild type are in reasonable agreement. However, the two approaches led to different explanations for the loss in stability. To analyze the differences, a series of refinements based on the crystallographic data were performed, a number of aspects of the simulations were reexamined, and continuum electrostatic calculations were done to complement the latter. The results of those comparisons provide a better understanding of the origin of the free energy difference in this mutant. Furthermore, they show the importance of the combined use of simulations and crystallography for interpreting the effects of mutations on the energetics of the system.
authors.affiliation: Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh 27695-7622, USA. carla_mattos@ncsu.edu
authors.forename: Carla
authors.initials: C
authors.lastname: Mattos
authors.forename: Justin D
authors.initials: JD
authors.lastname: Cohen
authors.forename: David F
authors.initials: DF
authors.lastname: Green
authors.forename: Bruce
authors.initials: B
authors.lastname: Tidor
authors.forename: Martin
authors.initials: M
authors.lastname: Karplus
mesh_terms: D017122:Bacteriophage T4 / Q000201:enzymology; D003198:Computer Simulation; D018360:Crystallography, X-Ray; D004795:Enzyme Stability; D006639:Histidine / Q000737:chemistry; D006860:Hydrogen Bonding; D008958:Models, Molecular; D009113:Muramidase / Q000737:chemistry / Q000235:genetics; D009154:Mutation; D011506:Proteins / Q000737:chemistry* / Q000235:genetics; D055672:Static Electricity
chemical_list: D011506:Proteins; D006639:Histidine; D009113:Muramidase