CHONDROITINASE ABC-RESISTANT SULFATED TRISACCHARIDES ISOLATED FROM DIGESTS OF CHONDROITIN/DERMATAN SULFATE CHAINS

Four kinds of sulfated trisaccharides resistant to chondroitinase ABC were isolated after chondroitinase B or ABC treatment of dermatan sulfate or various chondroitin sulfate isomers, respectively. Their composition was determined by chemical analysis and fast atom bombardment-mass spectrometry. Their structures were characterized by chondroitinase ACII digestion in conjunction with HPLC, and 500-MHz one- and two-dimensional H-1 NMR spectroscopy. All the four trisaccharides have in common the core saccharide sequence, alpha-L-Delta(4,5)HexpA-(1 --> 3)-beta-D-GalpNAc(1 --> 4)-D-GlcpA. A monosulfated component isolated from shark scapular cartilage chondroitin sulfate C or bovine aorta dermatan sulfate was elucidated as alpha-L-Delta(4,5)HexpA-(1 --> 3)-beta-D-GalpNAc6SO(3)(-)-(1 -->)-D-GlcpA or alpha-L-Delta(4,5)HexpA-(1 --> 3)-beta-D-GalpNAc4SO(3)(-)-(1 --> 4)-D-GlcpA, respectively. A disulfated component obtained from shark scapular cartilage chondroitin sulfate C or squid cartilage chondroitin sulfate E was identified as alpha-L-Delta(4,5)HexpA2SO(3)(-)-(1 --> 3)-beta-D-GalpNAc6SO(3)(-)-(1 --> 4)-D-GlcpA or alpha-L-Delta(4,5)HexpA-(1 --> 3)-beta-D-GalpNAc4SO(3)(-)6SO(3)(-)-(1 --> 4)-D-GlcpA, respectively. These trisaccharides are derived from the reducing termini of the parent polysaccharides. some of the trisaccharides could be derived from the reducing termini exposed by the peeling reaction during the alkaline treatment while some others may represent the cleavage sites exposed by tissue endo-beta-D-glucuronidase(s), indicating the presence of such enzyme(s) which may release chondroitin/dermatan sulfate fragments from proteoglycans.