The active site of human lysozyme (HL) consist of a cleft on the exterior of the enzyme. Press here to view the cleft. There are only two residues that are actually involved in the catalytic action of lysozyme. These are glutamic acid 35 and aspartic acid 53. Press here to view these two residues. The cleft with the active site has been shown to hold six rings of the NAM and NAG ligand which is catalyzed. The rings are labeled A through F and the bond catalysis occurs between ring D and E.. To view the cleft and active site with a two member inhibitory ligand press here. The six ring are held in place by hydrogen bonding to residues in the cleft. The exact bonds are uncertain but through various experiments it is predicted that the A ring hydrogen bonds to aspartic acid 102. Press here. The B ring is believed to hydrogen bond to residues Asp 102 and Gln 104. Press here. Residues Ala 108, Asn 60, and Trp 64 are predicted to form hydrogen bonds with ring C. Press here. Ring D which must be distorted to fit into the active site is held in place with hydrogen bonds to Asn 46, Ala 108, and Val 110. Press here. Ring E is presumed to hydrogen bond with Trp 34, and Glu 35. Press here. Finally ring D is thought to hydrogen bond to Ser 36, Trp 34, and Lys 33. [Song,1994] Press here.
