Kampatsikas I, Pretzler M, Rompel A. Identification of Amino Acid Residues Responsible for C-H Activation in Type-III Copper Enzymes by Generating Tyrosinase Activity in a Catechol Oxidase.
Angew Chem Int Ed Engl 2020;
59:20940-20945. [PMID:
32701181 PMCID:
PMC7693034 DOI:
10.1002/anie.202008859]
[Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Indexed: 12/12/2022]
Abstract
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 (CgAUS) was generated and the activity studies showed that the reactivity of the three conserved histidines (HisA2 , HisB1 , and HisB2 ) is tuned by their adjacent residues (HisB1 +1, HisB2 +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.
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