Catalytic Dehydrogenation of Hydroaromatic Compounds in Benzene. III. Compounds Containing Gem Dialkyl Groups
作者:Homer. Adkins、David C. England
DOI:10.1021/ja01177a002
日期:1949.9
Purification and some properties of UDP-xylosyltransferase of rat ear cartilage
作者:U. Pfeil、K.-W. Wenzel
DOI:10.1093/glycob/10.8.803
日期:2000.8.1
UDP-xylosyltransferase (UDP-D-xylose:proteoglycan core protein β-D-xylosyltransferase EC 2.4.2.26) initiates the formation of chondroitin sulfate in the course of proteoglycan biosynthesis. The enzyme catalyzes the transfer of D-xylose from UDP-D-xylose to specific serine residues in the core protein. A procedure for purification of xylosyltransferase from rat ear cartilage was developed which includes ammonium sulfate fractionation, chromatography on heparin–agarose, on Sephacryl S300 and finally a substrate affinity chromatography applying the dodeca peptide Q-E-E-E-G-S-G-G-G-Q-G-G. The specific activity of the purified enzyme was about 420 mU per mg protein. The purification factor was about 26.000 with 27% yield. In SDS-polyacrylamide gel electrophoresis, the highly purified enzyme is homogeneous and yields only a single distinct band of 78 kDa. An apparent molecular mass of 71 kDa was determined for the native enzyme. These data suggest a monomeric structure for the enzyme. Xylosyltransferase activity was found to depend essentially on the presence of divalent metal ions. The Km value for UDP-D-xylose was determined to 6.5 µmol/l and for the dodeca peptide Q-E-E-E-G-S-G-G-G-Q-G-G as xylose acceptor to 8 µmol/l.