chondroitin B lyase;
Acting on polysaccharides
chondroitin B lyase
Eliminative cleavage of dermatan sulfate containing (1->4)-beta-D-hexosaminyl and (1->3)-beta-D-glucurosonyl or (1->3)-alpha-L-iduronosyl linkages to disaccharides containing 4-deoxy-beta-D-gluc-4-enuronosyl groups to yield a 4,5-unsaturated dermatan-sulfate disaccharide (DeltaUA-GalNAc-4S).
This is the only lyase that is known to be specific for dermatan sulfate as substrate. The minimum substrate length required for catalysis is a tetrasaccharide . In general, chondroitin sulfate (CS) and dermatan sulfate (DS) chains comprise a linkage region, a chain cap and a repeat region. The repeat region of CS is a repeating disaccharide of glucuronic acid (GlcA) and N-acetylgalactosamine (GalNAc) [-4)GlcA(beta1-3)GalNAc(beta1-]n, which may be O-sulfated on the C-4 and/or C-6 of GalNAc and C-2 of GlcA. GlcA residues of CS may be epimerized to iduronic acid (IdoA) forming the repeating disaccharide [-4)IdoA(alpha1-3)GalNAc(beta1-]n of DS. Both the concentrations and locations of sulfate-ester substituents vary with glucosaminoglycan source .
Tkalec AL, Fink D, Blain F, Zhang-Sun G, Laliberte M, Bennett DC, Gu K, Zimmermann JJ, Su H
Isolation and expression in Escherichia coli of cslA and cslB, genes coding for the chondroitin sulfate-degrading enzymes chondroitinase AC and chondroitinase B, respectively, from Flavobacterium heparinum.