title: Flexibility and ligand exchange in a buried cavity mutant of T4 lysozyme studied by multinuclear NMR.
abstract: The Leu99-->Ala mutant of T4 lysozyme contains a large internal cavity in the core of its C-terminal domain that is capable of reversibly binding small hydrophobic compounds. Although the cavity is completely buried, molecules such as benzene or xenon can exchange rapidly in and out. The dynamics of the unliganded protein have been compared to the wild-type protein by measuring the NMR spin relaxation rates of backbone amide and side chain methyl nuclei. Many residues surrounding the cavity were found to be affected by a chemical exchange process with a rate of 1500 +/- 200 s(-1), which is quenched upon addition of saturating amounts of the ligand xenon. The relationship between the structure, dynamics, and energetics of the T4 lysozyme mutant is discussed.
authors.affiliation: Protein Engineering Network Centres of Excellence and Departments of Medical Genetics, Biochemistry, & Chemistry, University of Toronto, Toronto M5S 1A8, Ontario, Canada.
authors.forename: F A
authors.initials: FA
authors.lastname: Mulder
authors.forename: B
authors.initials: B
authors.lastname: Hon
authors.forename: D R
authors.initials: DR
authors.lastname: Muhandiram
authors.forename: F W
authors.initials: FW
authors.lastname: Dahlquist
authors.forename: L E
authors.initials: LE
authors.lastname: Kay
mesh_terms: D000409:Alanine / Q000235:genetics; D019943:Amino Acid Substitution / Q000235:genetics; D017122:Bacteriophage T4 / Q000201:enzymology* / Q000235:genetics*; D002247:Carbon Isotopes; D018360:Crystallography, X-Ray; D006859:Hydrogen; D007930:Leucine / Q000235:genetics; D008024:Ligands; D009113:Muramidase / Q000737:chemistry* / Q000235:genetics*; D009587:Nitrogen Isotopes; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods; D011485:Protein Binding / Q000235:genetics; D011487:Protein Conformation; D015202:Protein Engineering; D017510:Protein Folding; D011522:Protons; D011994:Recombinant Proteins / Q000737:chemistry* / Q000235:genetics*; D013816:Thermodynamics; D014978:Xenon / Q000737:chemistry
chemical_list: D002247:Carbon Isotopes; D008024:Ligands; D009587:Nitrogen Isotopes; D011522:Protons; D011994:Recombinant Proteins; D014978:Xenon; D006859:Hydrogen; D009113:Muramidase; D007930:Leucine; D000409:Alanine