Use of galactose oxidase in labelling hydroxylysine glycosides of collagen

Commercial preparations of galactose oxidase were shown to contain a proteolytic component active against collagen and collagen CNBr peptides which could not be inhibited by reagents such as EDTA, PMSF, PCMB and TLCK nor activated by Ca++ or Mn++. 30% of the total galactose oxidase activity could be recovered free of proteolytic activity in a simple one-step combined gel filtration/affinity chromatography procedure. The biological activity of such preparations was tested with reference to collagen hydroxylysine glycosides. It was shown that over 70% of the covalently linked tritium label introduced by KB3H4 reduction after galactose oxidase treatment was not associated with galactose but was present in the same non-specifically labelled components in control experiments. The enzyme could be used in a controlled manner to label hydroxylysine glycosides in collagen by immobilising it on agarose beads. In this form it was easy to store, re-usable and retained 95% of its original activity even after prolonged (18 h) incubation with substrates.