MMP1 (Welgus et al. 1981), MMP8 (Hasty et al. 1987), and MMP13 (Knauper et al. 1996) known in the literature as collagenases I, II and III respectively are able to digest the intrahelical bonds of collagen type I. MMP2, also known as Gelatinase-A, was found to cleave collagen type I fibrils (Aimes & Quigley 1995). Though this was disputed (Seltzre & Eisen 1999) there is a structural explanation for the apparent discrepancies in experimental data (Patterson et al. 2001). In addition trypsin-2 is able to degrade native soluble type I collagen (Moilanen et al. 2003).
Degradation is represented here at a theoretical end point where every alpha strand has been cleaved.