A simple and rapid analysis of total ascorbic acid (AsA) in serum and plasma and its automated analysis are described. AsA is oxidized by ascorbate oxidase (AsA oxidase) to dehydroascorbic acid that then reacts with o-phenylenediamine (OPDA) to form a quinoxaline derivative that absorbs at 340 nm. The change in absorbance is directly proportional to the total AsA concentration. The assay was va...

The L-ascorbate peroxidase 6 gene (APX6) is one of the most important genes for scavenging H2O2 and plays a vital role in plant resistance to environmental stresses. In this study, a novel ScAPX6 gene (GenBank Accession No. KT907352) was obtained from a sugarcane variety (ROC22). Bioinformatics analysis showed that ScAPX6 has a cDNA length of 1,086 bp and encoded 333 amino acid residues. Subcel...

Plants have evolved mechanisms to avoid and repair UV radiation damage; it is not surprising that photomorphogenic responses to UV-B and UV-C are often assumed to be adaptations to harmful radiation. Free radicals generated by UV are likely to be involved in the induction of antioxidant defence system. In this study plants were grown for 5 weeks in controlled conditions. Plants were grown in ve...

The present autlhors have isolated a particleassociated cytochrome oxidase from the phylloclades of cactus plant and studied its kinetics. To our knowledge, this is the first report on cytoclhrome oxidase from a crassulacean plant. Tender phylloclades of Nopalea dejecta SalmDyck were ground with 5 volumes of chilled medium in a Waring Blendor operated first at low speed for 25 seconds and then ...

Inhibition of xanthine oxidase (XO) in failing hearts improves cardiac efficiency by an unknown mechanism. We hypothesized that this energetic effect is due to reduced oxidative stress and critically depends on nitric oxide synthase (NOS) activity, reflecting a balance between generation of nitric oxide (NO) and reactive oxygen species. In dogs with pacing-induced heart failure (HF), ascorbate ...

Considering the economic importance of the tomato and its nutritional benefits to human health, a study was made of how two different environmental factors (temperature and overall solar radiation) influence the nutritional quality of cherry tomatoes during the plant full production cycle. Solanum lycopersicum L. cv. Naomi plants were grown in an experimental greenhouse. Three fruit samples wer...

Oxidative stress is induced by a wide range of environmental factors including heavy metals stress. Therefore, antioxidant resistance mechanisms may provide a strategy to enhance metal tolerance, and processes underlying antioxidant responses to metal stress must be clearly understood. In the present study, the effects of heavy metals generating antioxidative defense systems (i.e. superoxide di...

The ability of structural analogues of ascorbate to serve as substitutes for this reducing agent in the prolyl 4-hydroxylase reaction was studied. In experiments using the purified enzyme, variations of the compounds' side chain were compatible with co-substrate activity. The presence of very large hydrophobic substituents or a positively charged group caused an increase in the observed Km valu...