Biomedical subjects
Publications and source records attributed to C Paciolla.
A method for detection of ascorbic acid oxidase, ascorbic acid peroxidase and dehydroascorbic acid reductase is reported. This method allows the qualitative determination of the presence of these enzymes, also in conditions where the commonly used spectrophotometric assays are unreliable.
The rate of "in vivo" reduction of cytochrome c by ascorbic acid (AA) increases from 69 nmoles of cytochrome c for minute, to 202 nanomoles when ascorbate oxidase is added. Since the AA oxidation by AA oxidase is a system to generate ascorbic free radical (AFR), data suggest that AFR is a better reducing compound than ascorbate in cytochrome c reduction. Since the addition of oxidized glutathione and human immunoglobulins (-S-S- bridge containing compounds) in the medium produces a remarkable decrease in cytochrome c reduction, it is suggested that AFR could also reduce -S-S- groups.
Ascorbic acid content and redox-enzymes activities of AA system are determined in four population of Dasypyrum villosum adapted to live in different environments. In D. villosum from the driest and warmest environment (Pachino), AFR reductase and AA peroxidase have activities lower than in the other populations. The results point out the role of AA peroxidase as the main "scavenger" of the H2O2 produced by cell metabolism.
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The multiplicity of DHA reducing proteins has been observed by means of a native-PAGE technique in several plant species, thus demonstrating, in accordance with recent literature, that several differently evolved proteins are likely to perform DHA reduction. Moreover, a research strategy coupling the use of native-PAGE with chromatographic separation procedure, tentatively performed in Solanum tuberosum, proved to be a useful tool for the separation and partial identification of the proteins involved in DHA reduction.
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Galactonolactone dehydrogenase, a mitochondrial enzyme catalyzing the last step in ascorbate biosynthesis, is strongly inhibited by lycorine. A concentration of 10 microM of the alkaloid fully inhibits the activity of the enzyme. The high sensitivity of this enzyme to lycorine supports the hypothesis that the lycorine specifically inhibits ascorbate biosynthesis and that all the other metabolic responses to lycorine treatment depend on this primary inhibition of ascorbate biosynthesis.