Genetic variability of polyphenol oxidase (PPO) activity was evaluated in hexaploid, tetraploid, and aneuploid wheat (Triticum spp.). A DNA probe to kernel-specific PPO hybridized to PPO clones from an immature wheat kernel cDNA library but not to clones from a seedling cDNA library. Recombinant protein and antibody were developed from the kernel-specific PPO. PPO transcript and antigenic prote...

Polyphenol oxidase (PPO) was purified from fresh ginseng roots using acetone precipitation, carboxymethyl (CM)-Sepharose chromatography, and phenyl-Sepharose chromatography. Two isoenzymes (PPO 1 and PPO 2) were separated using an ion-exchange column with CM-Sepharose. PPO 1 was purified up to 13.2-fold with a 22.6% yield. PPO 2 bound to CM-Sepharose, eluted with NaCl, and was purified up to 22...

So far, azide has been consistently reported to act as an inhibitor of metal enzymes, especially copper proteins. The present work shows that azide can also act as an activator of polyphenol oxidase II (PPO II) from tobacco leaves. From the square-wave voltammetry of native PPO II, peroxide-PPO II complex and azide-PPO II complex, the reduction of nitro blue tetrazolium by the enzymes and activ...

The enzyme polyphenol oxidase (PPO) catalyzes the oxidation of phenolic compounds into highly reactive quinones. Polymerization of PPO-derived quinones causes the postharvest browning of cut or bruised fruit, but the native physiological functions of PPOs in undamaged, intact plant cells are not well understood. Walnut (Juglans regia) produces a rich array of phenolic compounds and possesses a ...

Polyphenol oxidase (PPO) is commonly believed to function as an effective antiherbivore defense in plants. PPO is induced in plants following herbivory, and insect performance is often negatively correlated with PPO levels. However, induced defenses create numerous changes in plants, and very little work has been done to test the direct effects of PPO on insect herbivores separately from other ...

The enzyme polyphenol oxidase (PPO) catalyzes the oxidation of phenolic compounds into highly reactive quinones. Polymerization of PPO-derived quinones causes the postharvest browning of cut or bruised fruit, but the native physiological functions of PPOs in undamaged, intact plant cells are not well understood. Walnut (Juglans regia) produces a rich array of phenolic compounds and possesses a ...

Polyphenol oxidases (PPOs) catalyze the oxidation of phenolics to quinones, the secondary reactions of which lead to oxidative browning and postharvest losses of many fruits and vegetables. PPOs are ubiquitous in angiosperms, are inducible by both biotic and abiotic stresses, and have been implicated in several physiological processes including plant defense against pathogens and insects, the M...

Insect prophenoloxidase (PPO) is an important innate immunity protein due to its involvement in cellular and humoral defense. It belongs to a group of type-3 copper-containing proteins that occurs in almost all organisms. Insect PPO has been studied for over a century, and the PPO activation cascade is becoming clearer. The insect PPO activation pathway incorporates several important proteins, ...

Plant polyphenol oxidases (PPOs) are widely distributed and well-studied oxidative enzymes, and their effects on discoloration in damaged and diseased plant tissues have been known for many years. The discovery in C.A. Ryan’s laboratory in the mid-1990s that tomato PPO is induced by the herbivore defense signals systemin and jasmonate, together with seminal work on PPO’s possible effects on her...

Polyphenol oxidase (PPO; EC 1.10.3.2) was isolated from wheat bran by a procedure that included ammonium sulfate fractionation, batch adsorption by DEAE-cellulofine, CM-cellulofine column chromatography, DEAE-cellulofine column chromatography, preparative isoelectric focusing, adsorption on the membrane of a Vivapure Q Maxi H spin column, and heat treatment. These procedures led to 150-fold pur...