Deeper inside the specificity of lysozyme when degrading chitosan. A structural bioinformatics study

Area of Science:

• Biochemistry
• Enzymology
• Structural Biology

Background:

• Lysozymes are crucial enzymes in various biological processes.
• Hen egg-white lysozyme is commonly used in in vitro studies of chitosan degradation.
• Human lysozyme exhibits higher activity and potential structural differences compared to hen egg-white lysozyme.

Purpose of the Study:

• To compare the structural and physicochemical properties of human and hen egg-white lysozymes.
• To investigate the interaction specificity between chitooligosaccharides and these lysozymes using molecular docking.

Main Methods:

• Sequence alignment to assess amino acid identity.
• Structural superimposition to evaluate overall structural similarity (RMSD calculation).
• Analysis of local physicochemical properties (electrostatic potential, hydrophobicity) of catalytic cavities.
• Molecular docking simulations to study enzyme-substrate interactions.

Main Results:

• Human and hen egg-white lysozymes share 60.47% sequence identity.
• Despite structural similarity (RMSD 1.198 Å), significant differences exist in local physicochemical properties of catalytic cavities.
• Amino acids involved in N-acetylchitohexaose interaction are conserved between the two lysozymes.
• Substrate specificity for chito-oligosaccharides is not clearly distinguishable but depends on molecular weight and deacetylation characteristics.

Conclusions:

• Human and hen egg-white lysozymes exhibit comparable substrate specificities for chito-oligosaccharides.
• Differences in catalytic cavity properties may influence enzyme activity and substrate binding.
• Further research is needed to fully elucidate the functional implications of these structural and physicochemical variations.