# What does a mixed inhibitor (as opposed to a competitive or non/uncompetitive inhibitor) do to the slope and y-intercept of a Lineweaver-Burk, or Double-Reciprocal plot?

##### 1 Answer

A **mixed inhibitor** changes both the slope and the y-intercept of a double-reciprocal plot.

In this case, you have to look at the equation that describes the **Lineweaver-Burk plot** for all the cases mentioned and figure out which one corresponds to the given criteria.

When no inhibitor is present, the Lineweaver-Burk equation looks like this

Now, when an **uncompetitive inhibitor** is present, the Lineweaver-Burk equation becomes

As you can see, the y-intercept changes, i.e. it goes up by a factor of

When a **competitive inhibitor** is present, the Linewaver-Burk equation becomes

This time, the slope of the line changes by a factor of

Finally, when a *mixed inhibitor** is present, the equation becomes

Now both the slope and the y-intercept change, the former by a factor of

**SIDE NOTE** *The terms* *and* *are actually a different notation for* *and for* *respectively*.