How do you guys remember if the increase or decrease in the presence of a competitive and noncompetitive inhibitor. I crammed it in my first year and never really understood the concept behind it. anyone care to explain?
the concept is this
a competitive inhibitor is going to try and bind in the exact same spot as the substrate. So, if the inhibitor is bound it will make it more difficult for the substrate to bind (which will change Km, since Km reflects binding affinity)
In a non competitive inhibitor (for the simplistic purposes of how we need to understand it) it binds to a totally different site on the enzyme, so theoretically the substrate could still get into the active site and bind (thus not affectin Km)
for Vmax, since the competitive inhibitor and sustrate are competing for that same site, whoever is in higher amount "wins" thus you can "compete out" the competitor..so you can still get to your vmax
with a non competitive inhibitor, it functions by altering the activitiy of the enzyme, so while it binds to a different site (and thus does not affect Km) it will alter Vmax, since no matter how much substrate you add wont "push off" the inhibitor
now for Km itself, always remember the lower the number the better the affinity. On Lineweaver burke plots you are looking at the inverse of Km at the x intercept, and the 1/Vmax on the y intercept, this a higher Km will be a smaller number on X, etc
hope this helps
