Background information
Matrix Metalloproteinase 8 (MMP8) is also known as neutrophil collagenase and collagenase 2. MMP8 degrades fibrillar collagens types I, II, III, aggrecan, serpins and alpha 2 macroglobulin. All collagenases cleave fibrillar collagens at one specific site resulting in generation of N terminal three quarter and C terminal one quarter fragments, which then denature to gelatin at body temperature. The substrate specificity of collagenases is variable: MMP1 degrades type III collagen more efficiently than type I or type II collagen, whereas MMP8 is more potent in degrading type I collagen than type III or type II collagen. MMP13, in turn degrades type II collagen 6 fold more efficiently than type I and type II collagens and displays almost 50 fold stronger gelatinolytic activity than MMP1 and MMP8. MMP8 is very similar to MMP1, sharing 57 % amino acid identity. Most cell types do not produce MMP8. Until recently, it was thought that MMP8 was produced exclusively by neutrophils, but it has also been detected in other cell types including arthritic chondrocytes and gingival fibroblasts. The human MMP8 gene has the chromosomal location of 11q22.2-22.3. MMP8 is heavily glycosylated, and the zymogen has a mass of 85 Kd. The zymogen is quickly activated to the 64 Kd form, and this breaks down to a cascade of active forms.
