biochemistry - Identifying type of inhibitor from $K_m$ and $V_{max}$

Apparently it is possible to identify whether an inhibitor is competitive or non-competitive from graphs of substrate concentration (x axis) and rate of reaction (y axis).

There needs to be a line for with inhibitor (constant concentration) and without inhibitor. The difference in $K_m$ and $V_{max}$ can then be interpreted to find out whether the inhibitor is competitive or not.

I know that if the effect of the inhibitor decreases with an increase in substrate concentration then inhibitor is competitive.

However I don't understand how to tell from the graphs mentioned earlier and $K_m$ and $V_{max}$. Could someone explain.

I have tried to google this but most of what comes up is scholarly articles which are beyond my level of understanding...

Answer

Competitive inhibitor competes for the active site. Therefore it will interfere with the binding of the substrate thereby increasing the apparent K_M.

A strictly non-competitive inhibitor does not compete for the active site. It however inhibits the catalysis by reducing the available molecules of active enzyme, E₀ (if it is a perfect inhibitor), thereby lowering the V_max.

There can be mixed inhibitors too and there can be different kinds of mixed inhibition. For example an inhibitor that interferes with catalysis and can also compete for the active site.

Depending on how you define K_M, a non-competitive inhibitor may or may not change it. If such inhibitor can bind to the enzyme at non-active site and reduce its k_cat, it changes the K_M as well as V_max in case of Briggs-Haldane kinetics.