The mechanism of initiation of chondroitin sulphate synthesis by beta-D-galactosides.
Embryonic chicken cartilage was incubated in vitro with phenyl-beta-[6-3H]galactoside and cycloheximide. Free chondroitin sulphate chains initiated by galactoside were isolated and degraded to yield 3-O-beta-D-glucuronosyl D-galactose (GlcA-Gal) derived from the sequence, GlcA-Gal-Gal-Xyl-Ser, which links the polysaccharide to protein. This enabled the distribution of 3H into specific galactose residues within the linkage oligosaccharide to be determined. Most of the 3H label (65%) was released as free galactose although 35% was recovered as GlcA-Gal. Similar experiments performed with unlabelled phenyl-beta-galactoside and [14C]galactose yielded 14C-labelled GlcA-Gal as a major product. We conclude that beta-galactosides initiate chondroitin sulphate synthesis primarily by serving as substrates for galactosyl transferase II.
Bradbeer
M
M
Department of Biochemistry, Monash University, Clayton, Vic., Australia.
Robinson
J A
JA
Robinson
H C
HC
D000818:Animals; D002240:Carbohydrate Sequence; D002356:Cartilage / Q000196:embryology / Q000378:metabolism; D002642:Chick Embryo; D002809:Chondroitin Sulfates / Q000096:biosynthesis* / Q000737:chemistry / Q000302:isolation & purification; D003513:Cycloheximide / Q000494:pharmacology; D004187:Disaccharides / Q000302:isolation & purification; D005697:Galactosides / Q000494:pharmacology*; D006868:Hydrolysis; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000302:isolation & purification / Q000378:metabolism; D011509:Proteoglycans / Q000302:isolation & purification; D014269:Trifluoroacetic Acid
D004187:Disaccharides; D005697:Galactosides; D009844:Oligosaccharides; D011509:Proteoglycans; C067751:3-O-beta-glucuronosylgalactose; C046399:phenyl-D-galactopyranoside; D002809:Chondroitin Sulfates; D003513:Cycloheximide; D014269:Trifluoroacetic Acid