What is PPO in food?
Polyphenol oxidase (PPO) is important in the beneficial coloration of some of our foods, such as prunes, dark raisins and teas. However, in most cases, PPO is the most damaging of enzymes in color deterioration (browning) of plant foods, with resulting losses of up to 50% for tropical fruits and others.
How do you calculate specific activity from absorbance?
You need to correlate the absorbance of the product released in your assay with standard product curve. By using y=mx+c, from your (Standard curve) you need to check the concentration of product released in term of micro gram. After identifying the amount of product release, then you can calculate Enzyme activity.
How do you calculate the total activity of an enzyme?
Total enzyme activity is obtained by calculating the dilution ratio of your assay. For instance, if you measure the OD of your catechol-1,2-dioxygenase with say 10 microliter of your enzyme preparation and that your enzyme preparation is 25 ml, your dilution ratio would be 2,500.
What is peroxidase assay?
Peroxidase Assay Kit uses H2O2 and an electron donor dye that forms a pink color during the peroxidase reaction. The optical density (570nm) or fluorescence intensity (λexc = 530nm, λem = 590nm) is a direct measure of the enzyme activity.
How does PPO enzyme work?
The enzyme polyphenol oxidase (PPO) catalyzes the oxidation of phenolic compounds into highly reactive quinones. Polymerization of PPO-derived quinones causes the postharvest browning of cut or bruised fruit, but the native physiological functions of PPOs in undamaged, intact plant cells are not well understood.
What class of enzyme is polyphenol oxidase?
Polyphenol oxidases (PPOs) are a group of copper-containing enzymes that catalyze the o-hydroxylation of monophenols to o-diphenols (tyrosinase activity, Enzyme Commission 1.14. 18.1) as well as the oxidation of o-diphenols to quinones (catecholase activity, Enzyme Commission 1.10. 3.2) in the presence of oxygen.
How do you calculate enzyme activity from mL to absorbance?
The put the both value of concentration and absorbance and obtained a equation in excel (Y=mc+X) put the value of absorbance in C. if you made a standard curve in mg/mL theen your enzyme activity will be mg/mL.
How do you calculate specific activity from Vmax?
The specific activity is Vmax/enzyme concentration. If the enzyme has only one substrate, then it is usually only necessary to measure the rate at a saturating substrate concentration, then divide by the enzyme concentration.
How do you calculate enzyme activity from absorbance?
How do you calculate the turnover number of an enzyme?
Enzyme units are expressed in µmoles, so we need to divide the specific activity by a million to convert to moles. Now if we divide the units per mole by the number of moles we get the turnover number per min. Dividing this by 60 gives the turnover number per sec. (Specific Activity x MW) / (1000 x 60).
How do you measure the activity of polyphenol oxidase?
The enzyme extract is mixed with catechol and Polyphenol Oxidase activity is measured spectrophotometrically by the rate of formation of 1,2 benzoquinone at 410nm. Estimates of activity (if available) and composition of the sample matrix.
What are polyphenol oxidases?
Polyphenol oxidases (PPOs) are ubiquitous in higher plants, and are also present in bacteria, fungi, and animals. They are bi-copper, oxygen-dependent, metalloenzymes which catalyze either one or two electron oxidations of phenols.551.
What is the reaction mixture for polyphenoloxidase activity?
The supernatant served as enzyme source and polyphenoloxidase activity was determined as given; the reaction mixture consisted of 1.5 ml of 0.1 M sodium phosphate buffer (pH 6.5) and 200 μl of the enzyme extract.
How do you measure the activity of peroxidase?
Peroxidase activity can be determined with Guaicol and hydrogen peroxide as substrate. 0.25%Substrate to be prepared in 100 mM potassium phosphate buffer pH 6, H2O2 conc 0.08% in water.Add the substrates and enzyme and measure the Absorbance at 436 nm for 5mins against an enzyme blank.