Abstract
Lysozyme hydrolyzes the glycosidic bonds between N-acetylmuramic acid and N-acetylglucosamine in peptidoglycans located in the bacterial cell wall. The mechanism of the hydrolysis reaction of lysozyme was first studied more than 50 years ago; however, it has not yet been fully elucidated and various mechanisms are still being investigated. One reaction system that has commonly been proposed is that the lysozyme intermediate undergoes covalent ligand binding during hydrolysis. However, these findings resulted from experiments performed under laboratory conditions using fluorine-based ligands, which facilitate the formation of covalent bonds between the ligands and the catalytic side chain of lysozyme. More recently, high-resolution X-ray structural analysis was used to study the complex of lysozyme with an N-acetylglucosamine tetramer. As a result, the carboxyl group of Asp52 was found to form a relatively strong hydrogen-bond network and had difficulty binding covalently to C1 of the carbohydrate ring. To confirm this hydrogen-bond network, neutron test measurements were successfully performed to a resolution of better than 1.9 Å.
Highlights
Lysozyme is a well known enzyme that hydrolyzes the glycosidic bonds between N-acetylmuramic acid and N-acetylglucosamine in peptidoglycans located in the bacterial cell wall
The reaction system that has most commonly been proposed is that the intermediate of lysozyme forms a covalent bond between the fourth carbohydrate ring and the side chain of Asp52 during hydrolysis (Vocadlo et al, 2001). These findings were obtained under laboratory conditions using fluorine-based ligands, which facilitate the formation of covalent bonds to the catalytic side chain of lysozyme
A high-resolution structural analysis of lysozyme complexed with an N-acetylglucosamine tetramer [(GlcNAc)4] was successfully performed using X-ray diffraction
Summary
Lysozyme is a well known enzyme that hydrolyzes the glycosidic bonds between N-acetylmuramic acid and N-acetylglucosamine in peptidoglycans located in the bacterial cell wall. After the binding of the carbohydrate ring hexamer to the catalytic site of lysozyme, hydrolysis occurs between the fourth and fifth carbohydrate rings via two catalytic amino acids, such as Glu and Asp in the case of hen egg-white (HEW) lysozyme. The reaction system that has most commonly been proposed is that the intermediate of lysozyme forms a covalent bond between the fourth carbohydrate ring and the side chain of Asp during hydrolysis (Vocadlo et al, 2001). These findings were obtained under laboratory conditions using fluorine-based ligands, which facilitate the formation of covalent bonds to the catalytic side chain of lysozyme. Many other structural analyses of lysozyme–carbohydrate complexes have been performed, such as complexes with tetra-N-acetylchitotetraose or a tetramer of N-acetyl-d-glucosamine [(GlcNAc)4] (Maenaka et al, 1995; Yamada et al, 2015), as well as a complex with tri-N-acetylchitotetraose (Cheetham et al, 1992)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Acta crystallographica. Section D, Structural biology
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
