Claus Kerkhoff1, Thomas Vogl1, Wolfgang Nacken1, Claudia Sopalla1, Clemens Sorg1
1Institute of Experimental Dermatology, von-Esmarch-Str. 56, 48149 Münster, Germany
Tóm tắt
Analysis of the calcium‐induced arachidonic acid (AA) binding to S100A8/A9 revealed that maximal AA binding was achieved at molar ratios of 1 mol S100A8 and 1 mol S100A9 and for values greater than 3 calciums per EF‐hand. The AA binding capacity was not induced by the binding of other bivalent cations, such as Zn2+, Cu2+, and Mg2+, to the protein complex. In contrast, the binding of AA was prevented by the addition of either Zn2+ or Cu2+ in the presence of calcium, whereas Mg2+ failed to abrogate the AA binding capacity. The inhibitory effect was not due to blocking the formation of S100A8/A9 as demonstrated by a protein‐protein interaction assay. Fluorescence measurements gave evidence that both Zn2+ and Cu2+ induce different conformational changes thereby affecting the calcium‐induced formation of the AA binding pocket within the protein complex. Due to the fact that the inhibitory effect of Zn2+ was present at physiological serum concentrations, it is assumed that released S100A8/A9 may carry AA at inflammatory lesions, but not within the blood compartment.
