A　gelatinolytic　matrix　metalloproteinase　(gMMP)　from　grass　carp　skeletal　muscle　was　purified　by　30-70%　ammonium　sulphate　fractionation　and　a　combination　of　chromatographic　steps　including　ion　exchange　on　DEAE-Sephacel,　gel　filtration　on　Sephacryl　S-200,　and　affinity　on　gelatin-sepharose.　The　molecular　weight　of　the　proteinase　as　estimated　by　SDS-PAGE　was　70　kDa　under　non-reducing　conditions.　The　enzyme　revealed　high　activity　from　30　to　50　C,　and　the　gelatin　hydrolysing　activity　was　investigated　at　a　slightly　alkaline　pH　range　using　gelatin　as　substrate.　Metalloproteinase　inhibitor　EDTA　completely　suppressed　the　gelatinolytic　activity,　while　other　proteinase　inhibitors　did　not　show　any　inhibitory　effect.　Divalent　metal　ion　Ca2+　was　essential　for　the　gelatinolytic　activity.　Further,　peptide　mass　fingerprinting　obtained　four　fragments　with　45　amino　acid　residues,　which　were　highly　identical　to　MMP-2　from　fish　species.　The　gMMP　could　effectively　hydrolyse　type　I　collagen　even　at　4　degrees　C,　suggesting　its　involvement　in　the　texture　softening　of　fish　muscle　during　the　post-mortem　stage.　(C)　2013　Elsevier　Ltd.　All　rights　reserved.