THE GELATIN-BINDING SITE OI HUMAN 72 KDA TYPE-IV COLLAGENASE (GELATINASE A)

To identify structures critical for gelatin-binding of 72 kDa type IV collagenase (gelatinase A), fragments of this metalloproteinase have b een expressed in Escherichia coli and assayed for their gelatin affini ty. Each of the three fibronectin-related type II domains was found to have affinity for gelatin. Fragments containing all three tandem type II domains had significantly stronger affinity than any of the consti tuent units, indicating that they co-operate to form the high-affinity gelatin-binding site. Competition experiments have also shown that ge latinase A binds more tightly to gelatin than fibronectin and can disp lace the latter from denatured collagen.