Potentials of purified tyrosinase from yam (Dioscorea spp) as a biocatalyst in the synthesis of cross-linked protein networks

We report the usefulness of yam tyrosinase as a catalyst in the synthesis of cross-linked protein networks for biopolymers. The enzyme was purified using aqueous two-phase partitioning (ATPs) and peptide mapping on SDS-PAGE was carried out to ascertain degree of similarities of tyrosinase from the yam species. The mapping revealed distinct peptide bands of 3, 4, 4 and 2 for tyrosinase from D. praehensilis, D. alata, D. rotundata and C. esculenta respectively purified using conventional method. In contrast, continuous broad band was noticed for the ATPS-purified enzymes due to bound polyethylene glycol (PEG). Tyrosinase from D. praehensilis with overall better properties was used in the synthesis of cross-linked protein networks. The enzyme catalyzed conversion of soluble proteins from whey, moringa leaves, pumpkin leaves and cow blood into fibrous (cross-linked) protein networks for improved properties and functionalities. The purified tyrosinase from D. praehensilis was also covalently bonded to bovine serum albumin (BSA) forming tyrosinase-BSA adduct with molecular weight of 118 ± 2.0 kDa, revealing its potential as a reporter enzyme by reporting BSA. The overall result further reinforces yam tyrosinase as an enzyme of interest in various biotechnological applications.