Interaction with heparin protects tissue transglutaminase against inactivation by heating and by proteolysis.

The considerable affinity of tissue transglutaminase for heparin was the basis for use of heparin-based affinity matrices for enzyme purification. Interaction of transglutaminase with heparin might mimic the physiological binding to membrane heparan sulfates, accounting for the limited but significant fraction of enzyme exposed at cell surface to crosslink ECM proteins. Exploring effects of heparin on transglutaminase activity and stability, we have noted that heparin only slightly affects activity in vitro, but the protein against heat treatment and proteolysis.