The susceptibility of three different solubilized forms of type IV collagen to gelatinase A cleavage and the concomitant effects on cell and integrin binding have been assessed. Dithiothreitol-solubilized Engelbreth-Holm Swarm (EHS) type IV collagen with disrupted intramolecular disulfide bonds in the CB3[IV] region was cleaved N-terminally to the CB3[IV] region into the two characteristic 100 -300-nm fragments at 30°C and was totally degraded at 37°C. This was reflected in the partial or total

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... loss of the ␣ 1 ␤ 1 and ␣ 2 ␤ 1 integrin binding sites within this region. The ability of gelatinase A to cleave EHS type IV collagen preparations with intact interchain disulfide bonds in CB3[IV] only occurred at higher temperatures. Furthermore, no effect on binding of cells or isolated integrins to the gelatinase-treated collagen could be detected after treatment at 37°C. Dimeric collagen IV of human placenta with intact disulfide bonds in the CB3[IV] region was not degraded at all by gelatinase A at 37°C.