Enzymatic inhibition and Lineweaver Burk plots. EC number Enzyme superfamily Enzyme family List of enzymes. Competitive inhibitors have the same y -intercept as uninhibited enzyme since V max is unaffected by competitive inhibitors the inverse of V max also doesn’t change but there are different slopes and x -intercepts between the two data sets. It also gives a quick, visual impression of the different forms of enzyme inhibition. So let’s talk about inhibition and how that affects enzyme kinetics. Start with the protein concentration for the PF that you calculated in the last assignment when it was undiluted. The same kinds of techniques we used before for the titration curves will be used. We can then plot this on a graph, with our Y-axis being one over V O, and our X-axis being one over S, and if we draw out the corresponding line, the slope of our line will be equal to Km over V max, and our Y-intercept will be equal to one over V max.

Start with the protein concentration for the PF that you calculated in the last assignment when it was undiluted. Analogously to our titration exercise, we will use the M-M equation as our model for the enzyme reaction system. Ignoring the known values for Km and Vmax, find them graphically from your plots. And using this idea you can derive the Michaelis-Menten equation, which is useful for quantitatively looking at how enzymes behave kinetically. For this exercise we need to set up columns for the various parameters in the Michaelis-Menten equation. Ignoring the known values for Km and Vmax, find them graphically from your plots. What are its problems? So in this case the inhibitor competes with substrate for space on the enzyme.

The lineweavsr reciprocal plot distorts the error structure of the data, and it is therefore unreliable for the determination of enzyme kinetic parameters. Under Forecastset Backward to 0.

Duplicate and copy your spread sheet columns capture the columns with the mouse, then click on a cell, say F, and hit enter:. But the enzyme will still be effective at low substrate concentrations, even with the inhibitor around, since there isn’t that same increase in slope.

If Microsoft Excel has already been accessed, select New from the File menu to display a new spreadsheet. Go to Insert – Chart Single click on the line of the graph for the uninhibited enzyme assay that is now displayed on the screen.

We can make one over V Bhrk our Y or dependent variable, Km over V max our coefficient m, or the slope, one over S our X, or independent variable, and then one over V max our b, or Y-intercept. So since you’re decreasing V max as you add more inhibitor, even if you really increase the substrate concentration, you won’t be able to overcome the effects of the inhibitor.

### BISC/S Lab 3 Calculations – OpenWetWare

Repeat steps 10 and 11 for the line graph of inhibited enzyme assay. Duplicate and copy your spread sheet columns capture the columns with the mouse, then click on a cell, say F, and hit enter:. Is IPTG an inhibitor or lineweager of the reaction? In the Options Folder of Trendline check off: How do these values compare to each other and to the “real” values.

In this case you’ll notice that all three lines have the same slope, but different increasing Y-intercepts. Next fill the substrate column with concentrations plto 0 – 5 Go to Edit – Fill – Serieswhen the dialog box comes up click on the radio button for columns under Series inthen set the step value to 0.

Second we learned about competitive, uncompetitive, and non-competitive inhibition. To log in and use all the features of Khan Academy, please enable JavaScript in your browser. Well, first we learned that we can rearrange the Michaelis-Menten equation to come up with a function for the Lineweaver-Burke plots. So now what we’re going to do is take what we just learned about inhibitors and apply it to the Lineweaver-Burke plots.

Under Chartselect Add Trendlineand choose Linear for type.

## Lineweaver–Burk plot

Analogously to our titration exercise, we will use the M-M equation as our model for the enzyme reaction system. Views Read Edit View history.

In other projects Wikimedia Commons. Under step 3, in the Titles Folder type the title in the chart title text box. Competitive inhibitors have the same y -intercept as uninhibited enzyme since V max is unaffected by competitive inhibitors the inverse of V max also doesn’t change but there are different slopes and x -intercepts between the two data sets.

So in this case the inhibitor competes with substrate for space on lineweavee enzyme. Journal of Chromatography B. Line two will represent some inhibitor being present, and line three will represent even more inhibitor being present. Now go back and add a line to the plot by going under ChartAdd Trendline.

The same kinds of techniques we used before for the titration curves will be used.

## BISC220/S11: Lab 3 Calculations

From Wikipedia, the free encyclopedia. In the dialog boxes choose linear, then double-click on the line and under options choose display equation and r-squared Although it is still used for representation of kinetic data, [2] non-linear regression or alternative linear forms of the Michaelis—Menten equation such as the Hanes-Woolf plot or Eadie—Hofstee plot are generally used for the calculation of parameters.

We can then plot this lijeweaver a graph, with our Y-axis being one over V O, and our X-axis being one over S, and if we draw out the corresponding line, the slope of our line will be equal to Km over V max, and our Y-intercept will be equal to one over V max.

And it gives us another way to look into the Linewevaer equation. A line plot of the Lineweaver-Burk data for the uninhibited and inhibited enzyme reactions will be displayed.