Collagen as a Substrate for Tissue Transglutaminase

Abstract

Heat-denatured (60°C for 1 h) unlabelled and [125I]-labelled type I and type III calf skin collagers were found to be crosslinked into high molecular weight polymers by guinea pig liver transglutaminase as demonstrated by SDS gel electrophoresis. Transglutaminase catalyzed incorporation of [14C]-putrescine into all subunits of denaturated collpgen of both types. This enzyme also catalyzed the formation of co-crosshnks between denaturated type I and III collagens and fibrinogen, fibrin as well as fibrin already crosslinked by factor XIII. Factor XIII was not effective ir-induction of these reactions. Non-denatured collagens both soluble and in the forn. of reconstituted fibrils were neither crosslinked nor co-crosslinked with fibrin and fibrinogen by liver transglutaminase. The results presented indicate that glutamine and lysine residues cf collagen in its native state are not accessible for liver transglutaminase, vhich catalyzes formation of crosslinking glutamyl bonds.