The Metal Ion Requirement for Activation of Latent Collagenase from Human Polymorphonuclear Leucocytes

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Abstract
Latent human PMN [polymorphonuclear] leukocyte collagenase (enzyme-inhibitor complex) was shown to require Zn for the property of being activatable by various disulfides. The active enzyme also requires Zn for activity, indicating a possible participation in the enzyme''s reaction mechanism and/or stabilization of the active site. The Zn in the latent enzyme may be removed by dialysis against EDTA or cysteine. This produces a Zn-free latent enzyme which cannot be activated by any of the disulfide-containing activators. Readdition of Zn to the EDTA-inhibited latent enzyme, at the same concentration as the EDTA, produces an activatable latent enzyme once again. Excessive Zn concentrations (> 3 times the concentration of EDTA) exhibited an inhibitory effect on the activation process. Thereafter the inhibitor cannot be removed by disulfides from the enzyme-inhibitor complex of the latent enzyme. The Zn in the latent enzyme may be replaced by other double-positive metal ions such as Co, Mn, Mg and Cu.