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Identification of Amino Acid Residues Responsible for C−H Activation in Type‐III Copper Enzymes by Generating Tyrosinase Activity in a Catechol Oxidase
Author(s) -
Kampatsikas Ioannis,
Pretzler Matthias,
Rompel Annette
Publication year - 2020
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.202008859
Subject(s) - tyrosinase , chemistry , hydroxylation , stereochemistry , catechol oxidase , enzyme , catechol , oxidase test , active site , residue (chemistry) , substrate (aquarium) , tyrosine , biochemistry , polyphenol oxidase , biology , peroxidase , ecology
Tyrosinases (TYRs) catalyze the hydroxylation of phenols and the oxidation of the resulting o ‐diphenols to o ‐quinones, while catechol oxidases (COs) exhibit only the latter activity. Aurone synthase (AUS) is not able to react with classical tyrosinase substrates, such as tyramine and l ‐tyrosine, while it can hydroxylate its natural substrate isoliquiritigenin. The structural difference of TYRs, COs, and AUS at the heart of their divergent catalytic activities is still a puzzle. Therefore, a library of 39 mutants of AUS from Coreopsis grandiflora ( Cg AUS) was generated and the activity studies showed that the reactivity of the three conserved histidines (HisA 2 , HisB 1 , and HisB 2 ) is tuned by their adjacent residues (HisB 1 +1, HisB 2 +1, and waterkeeper residue) either to react as stronger bases or / and to stabilize a position permissive for substrate proton shuffling. This provides the understanding for C−H activation based on the type‐III copper center to be used in future biotechnological processes.