Functionality study of Na sub(6)PMo sub(11)FeO sub(40) as a mushroom tyrosinase inhibitor

The inhibitory effects of iron-substituted phosphomolybdic acid (Na sub(6)PMo sub(11)FeO sub(40), abbreviated as PMo sub(11)Fe) on mushroom tyrosinase were investigated. The Native-PAGE results show that PMo sub(11)Fe has an inhibitory effect on tyrosinase. A spectrophotometric analysis shows that PMo sub(11)Fe is a reversible and noncompetitive inhibitor with K sub(I) = K sub(IS) = 0.47 mmol L super(-1). The effects of PMo sub(11)Fe on the preservation of lotus root slices were studied. The results show that PMo sub(11)Fe can significantly slow the browning rate of lotus root slices, inhibit the activity of polyphenol oxidase (PPO), enhance the activity of peroxidase (POD) and superoxide dismutase (SOD), maintain high levels of glutathione (GSH), ascorbic acid (ASA) and sucrose and control the peroxidation degree of fresh-cut fruits and vegetables. This study may help to elucidate the design of mushroom tyrosinase inhibitors of polyoxometalates (abbreviated as POMs) and a theoretical basis for the use of POMs to inhibit fruit spoilage. The Native-PAGE analysis of inhibitory effect of PMo sub(11)Fe on the diphenolase activity of mushroom tyrosinase. Tyrosinase is encoded by multi-gene family (Richter et al., 2012), the molecular weight are usually 30-34 kDa (Bernan et al., 1985), 42-46 kDa (Gerdemann et al., 2002; Wichers et al., 2003), 64-68 kDa (Wichers et al., 2003). Figure A is the electrophoresis analysis of protein molecular weight and species of mushroom tyrosinase, figure B is the inhibitory spectrum of Native-PAGE of PMo sub(11)Fe on mushroom tyrosinase. The figures confirm that three kinds of molecular weight of tyrosinase are all existed in the sample and with activity.