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 ...

In order to investigate physiological and biochemical changes of wheat under stress residue of Imazethapyr herbicide (Imazethapyr), an experiment was conducted in a completely randomized design with four replications in greenhouse conditions at university of Mohaghegh Ardebili. The treatments consisted of five dose levels of herbicide Imazethapyr (0, 0.011, 0.022, 0.033 and 0.044 micrograms of ...

A crude enzyme extract from Dioscorea esculenta var. fasiculata tissue subjected to ion exchange chromatography on DEAE-Sephadex A-50 column. This procedure resolved the extract into two main protein peaks one of which eluted through the column relatively unbound while the other protein peak which remained bound to the column was eluted with 1.0 M NaCl. Both protein peaks contained polyphenol o...

Polyphenoloxidase was purified from chloroplasts of broad bean leaves (Vicia faba L.) to apparent homogeneity. The enzyme was composed of two proteins with an apparent mass of 65 and 68 kilodaltons after sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The isolated enzyme contained covalently attached carbohydrates and bound concanavalin A, Phaseolus vulgaris erythroagglutinin, and Ri...

Increasing the polyunsaturated fatty acid (PUFA) composition of milk is acknowledged to be of benefit to consumer health. Despite the high PUFA content of forages, milk fat contains only about 3% of PUFA and only about 0.5% of n-3 fatty acids. This is mainly due to intensive lipid metabolism in the rumen (lipolysis and biohydrogenation) and during conservation (lipolysis and oxidation) such as ...

Sequencing of the genome of Ralstonia solanacearum revealed several genes that putatively code for polyphenol oxidases (PPOs). To study the actual expression of these genes, we looked for and detected all kinds of PPO activities, including laccase, cresolase, and catechol oxidase activities, in cellular extracts of this microorganism. The conditions for the PPO assays were optimized for the phe...

Polyphenol oxidase (PPO) is predominately associated with the detrimental effect of browning fruit and vegetables, however, interest within PPO containing forage crops (crops to be fed to animals) has grown since the browning reaction was associated with reduced nitrogen (N) losses in silo and the rumen. The reduction in protein breakdown in silo of red clover (high PPO forage) increased the qu...

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) 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 co...