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...

In this work, we investigate various arithmetic properties of the function ppo(n), the number of overpartition pairs of n into odd parts. We obtain a number of Ramanujan type congruences modulo small powers of 2 for ppo(n). For a fixed positive integer k, we further show that ppo(n) is divisible by 2 k for almost all n. We also find several infinite families of congruences for ppo(n) modulo 3 a...

BACKGROUND Studies of perennial peanut (Arachis glabrata Benth.) suggest its hay and haylage have greater levels of rumen undegraded protein (RUP) than other legume forages such as alfalfa (Medicago sativa L.). Greater RUP can result in more efficient nitrogen utilization by ruminant animals with positive economic and environmental effects. We sought to determine whether, like red clover (Trifo...

polyphenol oxidase (ppo) activity varied in differentiation from hyphae to rhizomorph and croute in a. mellea. in undifferentiated hyphae there was not any ppo activity, while croute showed the highest activity. electrophoresis in the presence of sds allows the detection of intensive enzyme forms of ppo, and can also convert slower migrating enzyme forms to faster ones. some fluorescent compoun...

Melanosis is a major problem associated with the quality loss of Pacific white shrimp. This is mediated by polyphenoloxidase (PPO), in which biochemical and molecular properties can be varied with species, molting period, etc. The better understanding of PPO characteristics should pave a way for lowering melanosis, thereby extending the shelf life of Pacific white shrimp during handling and sto...

The more recent reports on polyphenol oxidase in plants and fungi are reviewed. The main aspects considered are the structure, distribution, location and properties of polyphenol oxidase (PPO) as well as newly discovered inhibitors of the enzyme. Particular stress is given to the possible function of the enzyme. The cloning and characterization of a large number of PPOs is surveyed. Although th...

The inducible expression of polyphenol oxidase (PPO), a presumed antiherbivore enzyme, was examined in hybrid poplar (Populus trichocarpa x Populus deltoides). Following mechanical wounding simulating insect damage, PPO activity increased dramatically in wounded and unwounded leaves on wounded plants beginning at 24 and 48 h, respectively. A hybrid poplar PPO cDNA was isolated and its nucleotid...