Chitinases, chitosanases, and lysozymes can be divided into procaryotic and eucaryotic families sharing a conserved core.
Barley chitinase, bacterial chitosanase, and lysozymes from goose (GEWL), phage (T4L) and hen (HEWL) all hydrolyse related polysaccharides. The proteins share no significant amino-acid similarities, but have a structurally invariant core consisting of two helices and a three-stranded beta-sheet which form the substrate-binding and catalytic cleft. These enzymes represent a superfamily of hydrolases which are likely to have arisen by divergent evolution. Based on structural criteria, we divide the hydrolase superfamily into a bacterial family (chitosanase and T4L) and a eucaryotic family represented by chitinase and GEWL. Both families contain the core but have differing N- and C-terminal domains. Inclusion of chitinase and chitosanase in the superfamily suggests the archetypal catalytic mechanism of the group is an inverting mechanism. The retaining mechanism of HEWL is unusual.
Monzingo
A F
AF
Department of Chemistry and Biochemistry, University of Texas, Austin 78712, USA.
Marcotte
E M
EM
Hart
P J
PJ
Robertus
J D
JD
D000595:Amino Acid Sequence; D000818:Animals; D002688:Chitinases / Q000737:chemistry* / Q000145:classification; D017124:Conserved Sequence; D019143:Evolution, Molecular; D006026:Glycoside Hydrolases / Q000737:chemistry* / Q000145:classification; D008969:Molecular Sequence Data; D009113:Muramidase / Q000737:chemistry* / Q000145:classification; D011487:Protein Conformation; D017433:Protein Structure, Secondary
D006026:Glycoside Hydrolases; C019868:chitosanase; D002688:Chitinases; D009113:Muramidase