Some Biochemical properties of polyphenoloxidase from spearmint (Mentha arvensis)

Abstract

Polyphenoloxidase (PPO; EC 1.14.18.1)

Browning inhibition mechanisms by cysteine, ascorbic acid and citric acid, and identifying PPO-catechol-cysteine reaction products

“…2b and c), ascorbic acid behaved similar to sulfides where it could reduce instantly the formed color and acted as quinone reducer. A lag period was reported before any observed increase in absorbance when ascorbic acid (Altunkaya and Gökmen 2008;Dincer et al 2002;Neves et al 2009) Fig. 3 UV-vis spectra of PPO assay under various conditions.…”

“…3 UV-vis spectra of PPO assay under various conditions. a absorbance of PPO assay at various periods, b catechol and ascorbic acid spectra at the assay concentrations, c adding ascorbic acid or cysteine after 10 min, and d adding citric acid at the beginning or after 10 min sulfites (Neves et al 2009) were used in PPO assays, which could be attributed to their reducing power toward quinone. Cysteine effect was also concentration dependent, it could also remove the developed color at higher concentrations (≥1.0 %) but its effect appeared after 120 s, not instantly as in sulfides and ascorbic acid, indicating its reactivity towards quinone but in a slower reaction rate.…”

Thermal inactivation kinetics of peroxidase and polyphenol oxidase from pomegranate arils ( Punica granatum L. cv. Wonderful)

“…The PPO showed the highest activity when pyrogallol was used as a substrate (100%), followed by 4-methyl catechol (67.44%), gallic acid (59.63%), catechol (33.71%), F I G U R E 2 Activity of POD and PPO as a function of substrate concentrations and Lineweaver-Burk plots using guaiacol as substrate for POD (a), H 2 O 2 substrate for POD (b), and pyrogallol for PPO (c) from pomegranate arils tyrosine (28.56%), and resorcinol (12.03%). PPO from various plant sources has been shown varying substrate specificity as reported in the literature (Aydemir, 2004;Dogan, Turan, Ertürk, & Arslan, 2005;McLarina & Leunga, 2020;Neves, Picchi, & Da Silva, 2009). POD reduces H 2 O 2 to water while oxidizing a variety of substrates (Nokthai, Lee, & Shank, 2010).…”

Co-Immobilization of Peroxidase and Tyrosinase onto Hybrid Membranes Obtained by the Sol-Gel Method for the Construction of an Optical Biosensor

“…For l-tyrosine as a substrate the ph optimum of tyrosinase is 7.5. other authors (8,15) who studied the ph optimum of tyrosinase with different substrates and found values of pH = 6.0 for catechol, of pH = 5.0 for chlorophenol, of pH = 5.5 for r-cresol, of pH = 7.0 for phenol. The activity of the tyrosinase can be modulated by adding organic solutions such as isopropanol etc.…”