How do you calculate relative activity of an enzyme?
Enzyme activity = moles of substrate converted per unit time = rate × reaction volume. Enzyme activity is a measure of the quantity of active enzyme present and is thus dependent on conditions, which should be specified.
What is total activity of enzyme?
Total activity is the total number of enzyme activity units (U) recovered at each step (and present in the sample from that step). It will usually decrease during purification, because protein is lost in various steps, and protein is also denatured during manipulations.
What is Vmax and Km?
Vmax is the maximum rate of an enzyme catalysed reaction i.e. when the enzyme is saturated by the substrate. Km is measure of how easily the enzyme can be saturated by the substrate. Km and Vmax are constant for a given temperature and pH and are used to characterise enzymes.
What is the difference between specific activity and total activity?
Total activity is measured by the enzymatic activity in the volume of fraction used in the assay multiplied by the fraction’s total volume. Specific activity is the total activity divided by total protein. The yield is the amount of activity retained after each purification step.
What is specific activity formula?
As specific activity is units of enzyme per mg protein, first calculate the mg protein in the sample. The sample volumes are in µl, whereas the protein concentration is in mg/ml, so you need to divide the latter by 1000 to get mg/µl. In summary, specific activity = enzyme units / (vol.
How do you calculate relative activity?
5- To calculate the relative activity just divide the enzyme activity in the presence of factor over that in its absence.
What does Ki mean in enzyme kinetics?
inhibitor constant
Ki, the inhibitor constant The inhibitor constant, Ki, is an indication of how potent an inhibitor is; it is the concentration required to produce half maximum inhibition. Plotting 1/v against concentration of inhibitor at each concentration of substrate (the Dixon plot) gives a family of intersecting lines.
What is enzyme kinetics in biochemistry?
Enzyme kinetics is the study of the rates of enzyme-catalysed chemical reactions. In enzyme kinetics, the reaction rate is measured and the effects of varying the conditions of the reaction are investigated. Reactions with three or four substrates or products are less common, but they exist.
What is the difference between allosteric enzyme and normal enzyme?
Allosteric enzymes are unique compared to other enzymes because of its ability to adapt various conditions in the environment due to its special properties. The special property of Allosteric enzymes is that it contains an allosteric site on top of its active site which binds the substrate.
Why is Phosphofructokinase important?
Phosphofructokinase-1 (PFK-1) is one of the most important regulatory enzymes (EC 2.7. 1.11) of glycolysis. PFK is able to regulate glycolysis through allosteric inhibition, and in this way, the cell can increase or decrease the rate of glycolysis in response to the cell’s energy requirements.
What is IC50 and Ki?
By definition, IC50 is the “total” concentration of inhibitor needed to reach 50\% inhibition; while Ki is the “free” concentration of inhibitor required to reach 50\% enzyme saturation. Therefore, IC50 is dependent on the enzyme concentration, and is always larger than Ki.
What is enzymatic activity and specific activity?
Enzyme activity and specific activity are two enzyme units which measure the enzymatic activity. Both measurements are important to determine the available enzymes in a mixture. Moreover, they are important in the study of enzyme kinetics and enzyme inhibition.
How do you determine the relative activity of an enzyme?
Relative activity of enzyme if you study different factors affecting enzyme for example pH or ligands to detect inhibitor or activator of that activity. 3- Determine the enzyme activity now you have just absorbance and to convert into enzyme activity divide over slope then on time of incubation.
What is relative activity and how is it calculated?
Relative activity is the ratio between the activity of your sample of interest and the activity of the control sample and therefore expressed as a percentage. There is a free guide here. It uses ATPase as an example enzyme but the basic principles of how to work out enzyme activity apply generally.
How can I express enzyme activity in terms of protein concentration?
If so you can express the activity of each enzyme in terms of protein concentration. Estimate the activity of each enzyme under saturating substrate concentrations and then measure the protein concentration of the extract. Each enzyme activity can then be expressed per mg of protein.