Biochemical and structural characterization of tomato PPOs provide novel insights into substrate preference and the role of the gatekeeper residue. polyphenol oxidases from Solanum lycopersicum

Polyphenol oxidases (PPOs) contain the structurally similar enzymes tyrosinases (TYRs) and catechol oxidases (COs). Two cDNAs encoding pro-PPOs of tomato (Solanum lycopersicum) were cloned and heterologously expressed in E. coli.