Volumetric characterization of tri-N-acetylglucosamine binding to lysozyme.
Volumetric characteristics of protein recognition events determine the direction of pressure-induced shifts in the recognition reaction, while also providing insights into the structural, dynamic, and hydration changes. We report changes in volume, ΔV, and adiabatic compressibility, ΔK(S), accompanying the binding of tri-N-acetylglucosamine [(GlcNAc)(3)] to lysozyme at 25 °C in a pH 5.5 sodium acetate buffer. We interpret our measured changes in volume and compressibility in terms of changes in hydration and dynamic properties of the protein. On the basis of our ΔV data, we find that 79 ± 44 water molecules are released to the bulk from the hydration shells of the protein and the ligand. Our ΔK(S) data suggest a 4 ± 2% decrease in the mean-square fluctuations of the intrinsic volume of the protein, <δV(M)(2)> (or a 2% decrease in δV(M)). Thus, the trisaccharide-bound state of the enzyme is less hydrated, more rigid, and less dynamic compared to the unbound state. In general, we discuss the importance of volumetric insights into the molecular origins of protein recognition events.
Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, Ontario M5S 3M2, Canada.
Ikbae
I
Son
Yuen Lai
YL
Shek
David N
DN
Dubins
Tigran V
TV
Chalikian
D000818:Animals; D002645:Chickens; D008958:Models, Molecular; D009113:Muramidase / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D013050:Spectrometry, Fluorescence; D013816:Thermodynamics; D014312:Trisaccharides / Q000737:chemistry / Q000378:metabolism*; D014867:Water / Q000737:chemistry / Q000378:metabolism
D014312:Trisaccharides; D014867:Water; C019117:N,N',N''-triacetylchitotriose; C421864:hen egg lysozyme; D009113:Muramidase