Meaningless to distinguish active site and binding site?

[Kinase]

I just can't wrap my head around this statement, slightly ironic considering my name. Why not bother making a distinction? I guess they both are almost the same thing, but a binding site might not catalyze anything? But it's going to help the enzyme catalyze something probably. So they both lead to the same product?

Or does this have to do with the kinetics of these sites?

 

[chemisttree]

Better to start with your understanding of the term 'active site'. How could you bind your substrate at one location and perform the chemical transformation somewhere else? Either it's bound where the action is happening or it's just on the way there.

 

[Kinase]

Oh, that makes sense now. Why I didn't think this before is beyond me.

I think I got caught up in things like PkC that bind Ca and then something else. The Ca isn't being changed and the other thing that is being bound is. So I was thinking the Ca site isn't really catalytic or active in the same way that the site that does phosphorylation is. But I see what you're saying now, thank you!

So, where the reaction occurs is where the substrate binds, and where the substrate binds is where the reaction occurs. So simple...

 

[chemisttree]

... So simple...

Which is why I could answer it...