Catecholase activity associated with copper-S100B.
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 a type II copper center and is shown here to exhibit catecholase activity, the two-electron oxidation of catechols. The steady-state kinetics associated with the oxidation of several catecholamines has been probed in order to further characterize this activity. The evidence provided indicates that the catecholase chemistry is copper initiated. Superoxide dismutase has no effect on the rates of catecholamine oxidation catalyzed by Cu-S100B, establishing that superoxide is not produced during this reaction, ruling out an autoxidative mechanism. Addition of catalase to the Cu-S100B reaction with catechols reduces the amount of oxygen consumed by 50%, demonstrating that peroxide is released during this reaction. The release of peroxide is mechanistically distinct from the type III dinuclear copper proteins, catechol oxidase and tyrosinase.
Senior
SueAnn Z
SZ
Department of Chemistry, Hamilton College, Clinton, New York 13323, USA.
Mans
Laura L
LL
VanGuilder
Heather D
HD
Kelly
Kimberly A
KA
Hendrich
Michael P
MP
Elgren
Timothy E
TE
D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000737:chemistry; D004156:Catechol Oxidase / Q000737:chemistry* / Q000378:metabolism; D002417:Cattle / Q000378:metabolism; D003300:Copper / Q000737:chemistry* / Q000378:metabolism; D018360:Crystallography, X-Ray; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D009414:Nerve Growth Factors / Q000737:chemistry* / Q000378:metabolism; D000075023:S100 Calcium Binding Protein A7; D064568:S100 Calcium Binding Protein beta Subunit; D009418:S100 Proteins / Q000737:chemistry* / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism
D002135:Calcium-Binding Proteins; D009414:Nerve Growth Factors; D000075023:S100 Calcium Binding Protein A7; D064568:S100 Calcium Binding Protein beta Subunit; D009418:S100 Proteins; C089242:S100A7 protein, human; C579160:S100B protein, human; D003300:Copper; D004156:Catechol Oxidase; D013482:Superoxide Dismutase; D002118:Calcium