The formation of purpurogallin
was measured with a UV-visible spectrophotometer at 430nm.
The activity of PG-POD was expressed as [mu]mol purpurogallin
[min.sup.-1] [mg.sup.-1] protein.
production was determined by the increase in absorbance at 420 nm at 25[degrees]C for the first minute of the reaction.
formation was measured by a UV-visible spectrophotometer at 430 nm and its molar extinction coefficient (2.5 mmol [L.sup.-1] [cm.sup.-1]) was used to calculate the specific enzyme activity.
The amount of purpurogallin
formed was determined by measuring the absorbance at 420 nm against a blank and was measured as [micro]M purpurogallin
formed [g.sup.-1] FW.
One unit of POD was defined as the amount of enzyme that caused the formation of 1 mg of purpurogallin
The absorbancy of the purpurogallin
formed was taken at 420 nm at time (40, 100s) for polyphenol oxidase assay (Kar and Mishra, 1976).
After incubated for 2h, the purpurogallin
formed was extracted with 35 mL ether and determined by taking the absorbancy at 420 nm.
, a naturally occurring phenol, extracted from the plants of Quercus spp.
The reaction was stopped by the addition of 20% [H.sub.2]S[O.sub.4] and the purpurogallin
was extracted by ethyl ether.
as an antioxidant protector of human erythrocytes against lysis by peroxyl radicals.
The phenolic additives that were inactive in this study were chiefly those in which the phenolic -OH group was in an ortho position relative to other substituents, or where the 2,6 positions relative to the phenolic -OH group were occupied by other substituents, for example, additional -OH groups in the case of the gallates and purpurogallin
; bromine atoms in the case of tetrabromobisphenol A; or t-butyl groups in the case of 4,4'-methylenebis(2,6,-di-t-butyl phenol) [Chemical Abstracts Service (CAS) no.