Melanism is a common polymorphism in many insect species that also influences immune function. According to the thermal melanin hypothesis, ectothermic individuals from cooler environments have darker cuticles and higher polyphenol oxidase (PO) levels, which represent a better immunocompetence. In this study, the links among environmental temperature, melanism, and PO activity of Saccharosydne ...

Polyphenol oxidase (PPO) from tomatoes was extracted and partially purified through  (NH4)2SO4 precipitation, dialysis and ion exchange chromatography. The activity of polyphenol oxidase was investigated in solanum lycopersicum. Spectrophotometric method was used to assay the enzyme activity and the kinetic constants - maximum enzyme velocity (Vmax) and Michealis - Menten constant (Km). Of the ...

Various pharmacological approaches to potentiate the therapeutic actions of levodopa and reduce side-effects are reviewed. Of currently available drugs, anticholinergic agents and amantadine have been studied extensively. Inhibition of extracerebral decarboxylase appears to be the most promising new area of investigation, though experience is at present limited. Other methods discussed include ...

Coupled dinuclear copper oxygen cores (Cu2O2) featured in type III proteins (hemocyanin, tyrosinase, catechol oxidase) are vital for O2 transport and substrate oxidation many organisms. μ-1,2-cis peroxido dicopper (CP) have been proposed as key structures the early stages of binding these proteins; their reversible isomerization to other Cu2O2 directly relevant enzyme function. Despite relevanc...

Tyrosinases and catechol oxidases belong to the family of polyphenol oxidases (PPOs). Tyrosinases catalyze theo-hydroxylation and oxidation of phenolic compounds, whereas catechol oxidases were so far defined to lack the hydroxylation activity and catalyze solely the oxidation of o-diphenolic compounds. Aurone synthase from Coreopsis grandiflora (AUS1) is a specialized plant PPO involved in the...

m ~ m w . regeneration and alters forest community structure in southern Appalachian p=A, hardwood forests. Using paired plots and reciprocal litter transplants in forests Polyphenol oxidase; with and without R. maximum cover, we examined the influence of R. maximum on Protease; Leaf litter litter mass and quality, N cycling and soil extracellular enzymes. Standing stocks of soil organic matter...

With the objective of elucidating the mechanisms of dioxygen activation by transition metal complexes, we have investigated functional models of some metalloenzymes, such as phenoxazinone synthase and catechol oxidase, based on bisdimethylglyoximatocobalt(II) and -iron(II) complexes. Kinetic studies and the identification of intermediates permitted to establish a free radical mechanism. The cat...