6533b839fe1ef96bd12a5c09

RESEARCH PRODUCT

Switch between tyrosinase and catecholoxidase activity of scorpion hemocyanin by allosteric effectors

Heinz DeckerDorothea NilliusElmar Jaenicke

subject

TrisStereochemistrymedicine.medical_treatmentTyrosinaseDopamineAllosteric regulationActivated hemocyaninBiophysicsMagnesium ChlorideTyramineType 3 copper proteinchemical and pharmacologic phenomenaBiochemistryCatalysisSubstrate SpecificityScorpionschemistry.chemical_compoundEnzyme activatorAllosteric RegulationStructural BiologyHemolymphHemolymphGeneticsmedicineAnimalsCatechol oxidaseMolecular BiologyScorpion Pandinus imperatorbiologyMonophenol MonooxygenaseSpectrum AnalysisActive siteCatecholoxidaseHemocyaninCell BiologyEnzyme ActivationchemistryBiochemistryHemocyaninsbiology.proteinTyrosinaseCatechol Oxidase

description

AbstractPhenoloxidases and hemocyanins have similar type 3 copper centers although they perform different functions. Hemocyanins are oxygen carriers, while phenoloxidases (tyrosinase/catecholoxidase) catalyze the initial step in melanin synthesis. Tyrosinases catalyze two subsequent reactions, whereas catecholoxidases catalyze only the second one. Recent results indicate that hemocyanins can also function as phenoloxidases and here we show for the first time that hemocyanin can be converted to phenoloxidase. Furthermore, its substrate specificity can be switched between catecholoxidase and tyrosinase activity depending on effectors such as hydroxymethyl-aminomethan (Tris) and Mg2+-ions. This demonstrates that substrate specificity is not caused by a chemical modification of the active site.

yearjournalcountryeditionlanguage
2008-02-05FEBS Letters
10.1016/j.febslet.2008.01.056http://dx.doi.org/10.1016/j.febslet.2008.01.056