Partial characterization of bean and maize root peroxidases and their ability to crosslink potato protein

Abstract

Two fractions of Class III peroxidases (POX; EC 1.11.1.7), soluble and ionically bound to the cell wall, were partially purified from bean and maize roots and characterized. According to the measured Km, both the soluble and ionically bound to the cell wall fractions of POX had high affinity for H2O2 and the high specificity for caffeic acid. Approximate molecular weights of POX in their tertiary (native) structure were determined by modified sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis (PAGE). Proteomic analysis resolved the identity and pI of different enzyme bands. The ability of maize and bean soluble peroxidase to crosslink native potato proteins was evaluated. The results obtained by SDSPAGE showed that both POX enzymes were capable of crosslinking potato protein, in particular patatin, a globular protein, with and without the presence of H2O2. To investigate the possible role of phenolic compounds in facilitating crosslinking, commercial horseradish peroxidase (HRP) with/without the addition of caffeic acid was used to crosslink potato protein. Information provided here could be useful for the purification of POX from maize and bean roots and for examination of protein-protein interactions.