Inhibition and the plots- MCAT

K_m

Inversely related to affinity to the substrate

Competitive inhibition effect on K_m

it increases

meaning affinity has decreased

Competitive inhibition change on V_max

no change

Overall effects on equation with Competitive inhibition

increases substrate

Uncompetitive inhibition change in K_m

it is decreased

meaning increases affinity

Image above shows

competitive inhibition

increase in K_m

no change in V_max

Uncompetitive inhibition effect on V_max

it is decreased

Effect on equation with uncompetitive inhibition

forms an ESI that cannot react and binds to an allosteric site

This image shows the MM graph of what

uncompetitive inhibition

notice change in both V_max and K_m

Mixed inhibition effect on K_m if it binds to enzyme

increase in K_m

Mixed inhibition effect on K_m if it binds to enzyme substrate

decrease in K_m

Effect of V_max in mixed inhibition

often times it is decreased as long as it can bind to the ES complex

Non-competitive inhibition effect on K_m

No change

Non-competitive inhibition effect on V_max

Decreased because mixed inhibition

Noncompetitive inhibition

mixed inhibition where the inhibitor has equal affinity for E and ES

This is a graph of

noncompetitive inhibition

notice no change in K_m but change in V_max

Lineweaver burk plot overview

Linear line where Y=MX+B

Slope of lineweaver

K_m/V_max

X-intercept of lineweaver burke

-1/K_m

Y-intercept of lineweaver burke

1/V_max

X-axis label for lineweaver burk

1/[S] meaning if you increase substrate concentration you get a smaller volume so increase in concentration goes left

Y-axis of lineweaver burk

1/V meaning greater V_max goes down the y-axis

What does a competitive inhibitor do to a lineaweaver

since competes with the substrate, decreases the affinity increasing K_m so dividing by a larger value meaning a smaller magintude of X-intercept (1/K_m) and does not change the V_max so y-intercept is the same.

Uncompetitive inhibitors on the Lineweaver burk

increases affinity of enzyme for substrate, so K_m decreases so a more negative value shifting X-intercept left. Also decreases V_max so the y-intercept goes up.

Gives parallel line

Noncompetitive inhibitors Lineweaver graph

decrease in V_max no change in K_m meaning no change in x-intercepts and a larger value in Y-intercept.