Effect of ascorbic acid, sodium bisulfite, and thiol compounds on mushroom polyphenol oxidase Academic Article uri icon

abstract

  • The effect of ascorbic acid, sodium bisulfite, glutathione (reduced), and dithiothreitol on the observed activity of mushroom polyphenol oxidase (PPO) was determined by spectrophotometry (color formation) and by polarography (0, uptake). By polarography, O2 uptake began immediately on adding enzyme. Ascorbic acid and sodium bisulfite had little effect on the initial velocity while dithiothreitol and glutathione decreased the initial velocity by 35%, with no further decrease at higher concentrations. By spectrophotometry, there was an initial lag in the absorbance change followed by a slower increase in absorbance than for the control at zero time. By spectrophotometry, the values were as follows: dithiothreitol, 0.06 mM; glutathione, 0.17 mM; sodium bisulfite, 0.20 mM; ascorbic acid, 0.24 mM. The direct effect of the reductants was determined by (1) incubation of the reductant with PPO and …

publication date

  • September 1, 1984