Matrix metalloproteinase-9 activity in ewes' milk and its relationship to somatic cell counts

The presence and the activity of gelatinase-B/matrix metalloproteinase 9 (MMP-9) in ewes' milk was evaluated with a particular focus on the possible correlation with the somatic cell count (SCC). Forty five individual milk samples obtained from lacaune sheep, previously analysed for SCC with values ranging from 5.0 × 104 to 1.6 × 107 cells mL−1, gave overall gelatinolytic activity between 0.53 ± 0.05 and 4.53 ± 0.55 fluorescence units min−1 mg−1 protein. Zymography showed that the variation in the gelatinolytic activity depended on variations in the specific activity of MMP-9; no significant differences in MMP-2 (gelatinase-A) activity were observed. Pearson's correlation calculations gave a fair correlation between the presence of somatic cells and the enzymatic activity. MMP-9 in the context of proteolytic activities related to the presence of somatic cells acquires greater importance taking into account the hydrolytic potential of MMP-9 versus casein, evaluated in this study by exploiting a molecular docking approach.