Heme-containing catalases and catalase-peroxidases catalyze the dismutation of hydrogen peroxide as their predominant catalytic activity, but in addition, individual enzymes support low levels of peroxidase and oxidase activities, produce superoxide, and activate isoniazid as an antitubercular drug. The recent report of a heme enzyme with catalase, peroxidase and penicillin oxidase activities i...

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...

A comparative chromatography of polyphenoloxidase isolated from barley, steeped barley, and green malt was made. It consisted ofextraction, precipitation, ion-exchange chromatography, gel filtration, and electrofocusing. Polyphenoloxidase was resolved into a high-molecularweight enzyme and a low-molecular-weight one. The proportion of the two enzymes underwent variations during malting. An incr...

Kinetic parameters for the thermal inactivation of several enzymes in carrot and potato homogenates have been determined. In carrots the most heat-resistant activity was polygalacturonase, followed by peroxidase and pectinmethylesterase. In potatoes peroxidase was the most resistant, followed by pectin methylesterase, polyphenol oxidase, and lipoxygenase. There were several notable similarities...

The effect of modifying polyphenol oxidase (PPO) and peroxidase (POX) activity during the extraction of virgin olive oil has been assessed in terms of its influence on the phenolic profile of the oil produced. These enzymes were modified by adding exogenous enzyme or specific inhibitors during the milling and subsequent kneading step, studying the effect on specific phenolic compounds in the oi...

Season-controlled changes in biochemical constituents viz. carotenoids (carotene and xanthophyll) and pectic substances along with IAA-oxidase and polyphenol oxidase (PPO) enzyme activities were estimated/assayed in leaves of Lycopersicon esculentum Mill. (tomato) in two developmental stages--pre-flowering (35 days after sowing) and post-flowering (75 days after sowing) in three different seaso...