A solvent deuterium isotope effect on the catalytic affinity (km) and catalytic constant (kcat) of tyrosinase in its action on different monophenols and o-diphenols was observed. The catalytic constant decreased in all substrates as the molar fraction of deuterated water in the medium increased, while the catalytic affinity only decreased for the o-diphenols with an R group in C-1 [-H, -CH3 and...

the removal performance of total poly phenols and orthodiphenols (o-diphenols) content in olive mill waste (omw) was investigated with a three stages cross flow laboratory scale rotating biological contactor (rbc) in the present study. due to high cod and other pollutant in the original omw, physico-chemical treatment was effected for cod and other pollutant reduction prior to biological treatm...

Tyrosinase usually catalyses the conversion of monophenols into o-diphenols and the oxidation of diphenols to the corresponding o-quinones. Sugumaran [(1986) Biochemistry 25, 4489-4492] has previously proposed an unusual oxidative decarboxylation of 3,4-dihydroxymandelate catalysed by tyrosinase. Our determination of the intermediates involved in the reaction demonstrated that 3,4-dihydroxybenz...

The removal performance of total poly phenols and orthodiphenols (o-diphenols) content in olive mill waste (OMW) was investigated with a three stages cross flow laboratory scale rotating biological contactor (RBC) in the present study. Due to high COD and other pollutant in the original OMW, physico-chemical treatment was effected for COD and other pollutant reduction prior to biological tr...

Latent phenoloxidase activity of hemocyanin (Hc) in whiteleg shrimp Penaeus vannamei was assayed to determine its potential involvement in postmortem melanosis. Conversion of pure 12-mer, but not 6-mer, hemocyanin to phenoloxidase by endogenous (serine proteinases) and exogenous (SDS) effectors demonstrated the need of complex aggregation for displaying enzyme activity. Because Hc was converted...

Tyrosinase is a natural enzyme and is often purified to only a low degree and it is involved in a variety of functions which mainly catalyse the o-hydroxylation of monophenols into their corresponding o-diphenols and the oxidation of o-diphenols to o-quinones using molecular oxygen, which then polymerizes to form brown or black pigments. The synthesis of o-diphenols is a potentially valuable ca...

8 2 ABSTRACT 9 The reaction between m-diphenols (resorcinol, 2-methylresorcinol, 2,5-10 dimethylresorcinol, 3-methylphenol, orcinol, and phloroglucinol) and 2-alkenals (2-11 pentenal and 2-octenal) was studied in an attempt to understand the chemical pathways 12 involved in the scavenging ability of m-diphenols for the 2-alkenals produced as a 13 consequence of lipid oxidation. Phenols reacted ...