In crystallo activity tests with latent apple tyrosinase and two mutants reveal the importance of the mutated sites for polyphenol oxidase activity.

ABSTRACT: Tyrosinases are type 3 copper enzymes that belong to the polyphenol oxidase (PPO) family and are able to catalyze both the ortho-hydroxylation of monophenols and their subsequent oxidation to o-quinones, which are precursors for the biosynthesis of colouring substances such as melanin. The first plant pro-tyrosinase from Malus domestica (MdPPO1) was recombinantly expressed in its latent form (56.4 kDa) and mutated at four positions around the catalytic pocket which are believed to influence the activity of the enzyme. Mutating the amino acids, which are known as activity controllers, yielded the mutants MdPPO1-Ala239Thr and MdPPO1-Leu243Arg, whereas mutation of the so-called water-keeper and gatekeeper residues resulted in the mutants MdPPO1-Glu234Ala and MdPPO1-Phe259Ala, respectively. Th

SUBMITTER: Kampatsikas I 

PROVIDER: S-EPMC5544008 | biostudies-literature | 2017 Aug

REPOSITORIES: biostudies-literature