Line-Weaver Burke Equation

Memory Hack💡

Something that you will probably be asked on an exam is what graph you are looking at. To rememebr this is the lineweaver-burke, remember that this is the reciprocal. So if you see 1/(anything), you should know which graph it is. 

Also keep in mind that since this is the recirpocal, you are going to need to do the inverse to find the ACTUAL value. 

Trick: "Lineweaver" is like you are "weaving the line" aka modifying it... Therefore, it is upsidedown (or the reciprocal)!

Notes

The Line-Weaver Burke equation is: 

1/Vo = (Km/(Vmax[S])) + (1/Vmax)

This is the double reciprocal of the michaelis menten equation, Vo = Vmax[S] / (Km + [S]) 

Because the Lineweaver–Burk equation produces a straight line, it is easier to determine more precise values of Vmax and Km. This is especially useful because Vmax is difficult to estimate directly from a Michaelis Menten plot. Since the graph approaches Vmax asymptotically, the exact value can be difficult to determine from the limited graphing range. Converting the data into this linear form allows these values to be calculated more accurately.

As you can see, for this graph we have changed the X and Y axis once again. For this plot, our X axis is now 1/[S] and our Y axis is now 1/Vo. This means that we can calculate Vmax and Km from the X and Y intercepts. For a reminder, the X intercept is where the line crosses the X axis (horizontal) and the Y intercept is where the line crosses the Y axis (vertical). 

The X intercept will tell us what the value of 1/Km is, which means that to find the actual Km value, we have to find the inverse of the X intercept on a line-weaver burke plot. (Reminder, you do this by calculating 1/(X-intercept) or simply pressing the inverse button (X^-1) on your calculator). 

Similarly, the Y intercept will tell us the value of 1/Vmax. Once again, to find the actual value of Vmax, we will need to find the inverse of the Y-intercept. This can be done in exactly the same way. 

Knowing this information now, we can also conclude that the slope of the line (calculated by rise/run) will be Km/Vmax.