The biochemical anti-herbivore defense of trembling aspen (Populus tremuloides Michx.) was investigated in a molecular analysis of polyphenol oxidase (PPO; EC 1.10.3.2). A PPO cDNA was isolated from a trembling aspen wounded leaf cDNA library and its nucleotide sequence determined. Southern analysis indicated the presence of two PPO genes in the trembling aspen genome. Expression of PPO was fou...

Extracellular enzymes degrade complex organic compounds and contribute to carbon turnover in soils. We used physical fractionation procedures to investigate whether soil carbon is spatially isolated from degradative enzymes across a prairie restoration chronosequence in Illinois, USA. We found that carbon-degrading enzymes were abundant in all soil fractions, including macroaggregates, microagg...

Zhang X., Shao X. (2015): Characterisation of polyphenol oxidase and peroxidase and the role in browning of loquat fruit. Czech J. Food Sci., 33: 109–117. Polyphenol oxidase (PPO) and peroxidase (POD) were extracted from a new loquat fruit cultivar (Ninghaibai) and characterised using reliable spectrophotometric methods. In both cases, the optimum pH for PPO was 4.5 and 5 for POD, and their opt...

Biochemical changes occurred in roots of bur marigold and grapevine infected with Longidorus africanus. Phenols of infected root tips differed quantitatively from those of healthy root tips (optical density of 0.68 and 0.32, respectively). Column chromatography of the phenol extracts resulted in more fractions in the infected than in the healthy root extract. Of the enzymes involved in phenol m...

Rhodobacter sphaeroides 2.4.1(T) respires aerobically via a branched respiratory chain consisting of both cytochrome c oxidases and quinol oxidases. Here, genes from chromosome II encoding two distinct quinol oxidases have been characterized. The qoxBA genes encode a putative heme-copper quinol oxidase, whereas the qxtAB genes encode a quinol oxidase homologous to the cyanide-insensitive oxidas...

Tetrahydroprotoberberine and protoberberine alkaloids are a group of biologically active natural products with complex molecular scaffolds. Isolation from plants is challenging stereoselective synthetic routes, particularly methylated compounds limited, reducing the potential use these compounds. In this work, we describe chemoenzymatic cascades toward various 13-methyl-tetrahydroprotoberberbin...

The effect of different anti-browning agents on partially purified longan polyphenol oxidase (PPO) activity was investigated by spectrophotometry, using catechol as a phenolic substrate. For this purpose, L-cysteine, potassium metabisulfite, ascorbic acid, and citric acid were used to inhibit the activity of longan PPO at different concentrations (0-10 mM). Lcysteine was found to be the most po...