Age-related decrease in the activity of UDP-xylose:core protein xylosyltransferase in rat costal cartilage.
The activity of UDP-xylose:core protein xylosyltransferase (EC 2.4.2.26) in costal cartilage of young rats (3 months) and old rats (36 months) was measured. The enzyme activity in cartilage of young rats (mean +/- S.D.) is 3370 +/- 1440 Bq h-1 mg-1 DNA, which is about three times higher than that determined in cartilage of old rats (1090 +/- 520 Bq h-1 mg-1 protein). The amount of galactosamine-containing proteoglycosaminoglycans that are extractable with 4 M guanidinium chloride from cartilage is significantly higher in young rats (29.1 +/- 4.8 nmol GalN per mg cartilage wet weight) than in old animals (5.8 +/- 3.0 nmol GalN per mg cartilage wet weight). Thus, if xylosyltransferase activity is referred to the amount of galactosamine-containing proteoglycans in cartilage, nearly identical values are obtained (young rats, 80 +/- 30 Bq h-1 mumol-1 GalN; old rats, 85 +/- 35 Bq h-1 mumol-1 GalN). The results support the assumption that the synthesis of proteochondroitin sulfate is diminished in costal cartilage of old rats by a mechanism involving a reduced activity of xylosyltransferase.
D000375:Aging; D000818:Animals; D002356:Cartilage / Q000201:enzymology / Q000254:growth & development*; D006595:Hexosamines / Q000032:analysis; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008297:Male; D010430:Pentosyltransferases / Q000378:metabolism*; D011509:Proteoglycans / Q000302:isolation & purification; D051381:Rats; D011919:Rats, Inbred Strains; D000097608:UDP Xylose-Protein Xylosyltransferase
D006595:Hexosamines; D007770:L-Lactate Dehydrogenase; D010430:Pentosyltransferases; D011509:Proteoglycans; D000097608:UDP Xylose-Protein Xylosyltransferase