Differential susceptibility of type X collagen to cleavage by two mammalian interstitial collagenases and 72-kDa type IV collagenase.

摘要: We have studied the degradation of type X collagen by human skin fibroblast and rat uterus interstitial collagenases 72-kDa IV collagenase. The attacked native helix at two loci, cleaving residues Gly92-Leu93 Gly420-Ile421, both scissions involving Gly-X bonds Gly-X-Y-Z-A sequences. However, enzymes displayed an opposite substantial selectivity for each these potential sites, with uterine enzyme catalyzing Gly420-Ile421 cleavage almost 20-fold faster than locus. Values enzyme-substrate affinity were approximately 1 microM indistinguishable from corresponding Km values against I collagen. Interestingly, in attacking collagen, manifested kinetic properties intermediate between those characterizing denatured substrates. Thus, energy dependence reaction velocity revealed a value EA 45 kcal, typical substitution D2O H2O solvent buffer failed to slow collagenolysis significantly (kH/kD = 1.1), contrast 50-70% slowing 2-3) observed collagens. Since this lack deuterium isotope effect is characteristic collagenase collagens, we investigated capacity another metalloproteinase gelatinolytic activity, collagenase, degrade cleaved 25 37 degrees C, loci close proximity enzymes. No further cleavages either temperature although kcat not determined (due associated tissue inhibitor metalloproteinases-2), catalytic rates appeared be comparison In contrast, was completely resistant proteolysis stromelysin. Type thus appears highly unusual its susceptibility member gene family.