Pyoverdine-type siderophores from fluorescent Pseudomonas species were purified by Zn2+-chelate chromatography, and their matrix metalloproteinase-2 (MMP-2) inhibition and metal-ion-chelating activities were studied. Structurally different pyoverdines showed different MMP-2 inhibition activities, and the inhibition activity was correlated with Zn2+-chelating activity. The IC50 value of a pyoverdine (P-113A1-2, MW 1187) for MMP-2 was 0.27 mug/ml (0.23 muM).