CLEAVAGE OF NATIVE TYPE-I COLLAGEN BY HUMAN NEUTROPHIL ELASTASE

The ability of purified human neutrophil elastase (EC 3.4.21.37) to cl eave native type I collagen has been investigated. Soluble human, bovi ne or rat type I collagen was incubated with neutrophil elastase for 1 6 h at 25 degrees C before catalysis was stopped with 3,4-dichloroisoc oumarin. Analysis by SDS/PAGE of the collagen digests revealed 3/4-len gth fragments similar in size to those produced by interstitial collag enase. The collagenolytic activity was dose dependent and was not due to a contaminating metalloproteinase or cysteine proteinase, as it was not inhibited by 1,10-phenanthroline, EDTA or ans-epoxysuccinyl-leucy lamido-(4-guanidino)butane. The identity of the cleavage products was confirmed using a new antibody that recognizes the unwound alpha 2(I)- chain. This detected the 3/4-length fragment of type I collagen follow ing neutrophil elastase cleavage. In addition to cleaving soluble coll agen, neutrophil elastase also cleaved reconstituted, radiolabelled ty pe I collagen fibrils, at a rate of 16 mu g/min per nmol. These result s indicate that neutrophil elastase can cleave native type I collagen in the helix, an activity that might contribute to its roles in connec tive-tissue pathology.