| Abstract
| - This study addresses the spectroscopic properties and reactivity associated with the copper-loaded form of S100B isolated from bovine brain. Copper(II)-S100B displays EPR features typical of atype II copper center and is shown here to exhibit catecholase activity, the two-electron oxidation ofcatechols. The steady-state kinetics associated with the oxidation of several catecholamines has been probedin order to further characterize this activity. The evidence provided indicates that the catecholase chemistryis copper initiated. Superoxide dismutase has no effect on the rates of catecholamine oxidation catalyzedby Cu-S100B, establishing that superoxide is not produced during this reaction, ruling out an autoxidativemechanism. Addition of catalase to the Cu-S100B reaction with catechols reduces the amount of oxygenconsumed by 50%, demonstrating that peroxide is released during this reaction. The release of peroxideis mechanistically distinct from the type III dinuclear copper proteins, catechol oxidase and tyrosinase.
|
