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1H-NMR study on the chitotrisaccharide binding to hen egg white lysozyme
T Fukamizo1, Y Ikeda, T Ohkawa
1Department of Biophysical Chemistry, Faculty of Agriculture, Kinki University, Japan.
European Journal of Biochemistry
|November 15, 1992
Summary
Investigating hen egg white lysozyme and chitotrisaccharide interactions using NMR revealed that acetylation of the saccharide and modification of Asp101 reduce conformational changes in the lysozyme binding site.
Area of Science:
- Biochemistry
- Structural Biology
- Biophysics
Background:
- Hen egg white lysozyme is a crucial enzyme in innate immunity.
- Understanding lysozyme's substrate binding is key to enzyme mechanism studies.
- Chitotrisaccharides are fragments of chitin, a natural polymer that lysozyme degrades.
Purpose of the Study:
- To investigate the interaction between hen egg white lysozyme and partially acetylated chitotrisaccharides.
- To elucidate the role of acetylation and specific amino acid modifications on lysozyme's conformational changes during saccharide binding.
Main Methods:
- 1H-NMR spectroscopy was employed to monitor changes in lysozyme.
- Partially acetylated chitotrisaccharides (mono-, di-, and triacetyl) were used as ligands.
- Chemically modified lysozyme, specifically Asp101-mutated, was utilized.
Main Results:
- Binding of triacetyl chitotrisaccharide [(GlcNAc)3] caused a significant upfield shift in the Trp28 C5H signal, indicating conformational changes in the adjacent hydrophobic box.
- The magnitude of this chemical shift change was smaller for partially deacetylated chitotrisaccharides.
- Modification of Asp101 in lysozyme also reduced the chemical shift change upon (GlcNAc)3 binding.
Conclusions:
- Saccharide acetylation and modification of Asp101 influence the conformational dynamics of hen egg white lysozyme's binding site.
- These findings suggest that deacetylation of sugar residues at subsites A and B, or modification of Asp101, diminishes the conformational response to saccharide binding.