Sandbox 42: Difference between revisions

Hen white lysozyme's substrate binding site accomodates six residue oligosaccharides. Glu 35 and Asp 52 are the enzyme's <scene name='Sandbox_42/Active_site/1'>active site residues</scene>active site residues. These residues have distinctly different microenvironments which are critical for their catalytic action. Asp 52 forms hydrogen bonds with surrounding residues including Asn46, Asp48, Ser50 and Asn59 on the anti-parallel beta-sheet and is negatively charged allowing for electrostatic stabilization of the reaction intermediate.<ref> PMID:19605465 </ref> Glu 35 conversely is surrounded by hydrophobic residues and its side chain stays protonated allowing for acid catalysis. Catalysis proceeds through the formation of a covalent intermediate. A mutation of T4 lysozyme allows for the product to stay bound to the enzyme. This mutation made it possible to isolate a <scene name='Sandbox_42/Ligand_and_lysozyme/1'>covalent enzyme-substrate intermediate</scene> which also shows the predicted distortion of the sugar in the 4th position of the active site.