Abstract
The activities and subcellular distribution of five glycosyltransferases involved in the biosynthesis of chondroitin sulfate by a transplantable rat chondrosarcoma were compared with the activities and distribution of the corresponding enzymes of normal embryonic rat and chick cartilage. Two important differences were found: 1) UDP- d-xylose:core protein β- d-xylosyltransferase was found in concentrations 10–15 times higher in the chondrosarcoma, and 2) all five glycosyltransferases were found to be more soluble in the chondrosarcoma. More than 90% of the xylosyltransferase activity could be extracted from the tumor without rupturing cells. This transferase exhibited optimal activity in solutions of 0.25 m KCl. The K m for the exogenous protein acceptor obtained by Smith degradation of bovine chondroitin sulfate-proteoglycan was 300 μg/ml; the K m for Ser-Gly-Gly, 30 m m. The activity of xylosyltransferase was maximal at pH 6.5 and was dependent upon the presence of Mg 2+ or Mn 2+. The K m for UDP-xylose was 5 × 10 −5, m. In view of the extraordinarily high level of xylosyltransferase activity found in the chondrosarcoma the authenticity of the xylosyl transfer reaction was verified by chemical characterization of [ 14C]xylose-labeled products.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
