Isolation of collagen glucosyltransferase as a homogeneous protein from chick embryos

Collagen glucosyltransferase was isolated as a homogeneous protein from chick embryos by a procedure consisting of ammonium sulphate fractionation, two affinity chromatographies and two gel filtrations. The specific activity of the purified enzyme was 32,000 times that of the 15,000 x g supernatant of the embryo homogenate, and the enzyme was pure when examined by sodium dodecyl sulphate polyacrylamide gel electrophoresis using three different gel compositions. The molecular weight of the enzyme was about 72,000-78,000 by sodium dodecyl sulphate polyacrylamide gel electrophoresis, the value being dependent on the gel composition. The apparent molecular weight by gel filtration was dependent on the purity and protein concentration. The sedimentation coefficient S20,w was 4.7. The data suggest that the enzyme molecule consists of one polypeptide chain.