[help784]

I recently took a test and there was some confusion as to my answer.  I was not marked wrong but the teacher said that that Vmax decreases and Km is usually not affected when it comes to irreversible inhibitors.  Is this right?  I put something else, but he just commented the above statement to me.  I am now studying for the final and need some clarification.  I can't find the answer in any of my books.   

[Yggdrasil]

Using an irreversible inhibitor is equivalent to decreasing the concentration of enzyme [E].  This will decrease V_max (because V_max = k_cat[E]), but the enzymes that remain will work fine (so K_m is unchanged).