enzyme conformational selection

Question 1

protein structures always undergoing…

Answer 1

changes . some are large and directed (ex: T to R, ligands binding/unbinding)
some are small like a proton transfer, which wont cause huge conformtional changes.

These operate on different time scales

Question 2

S binding and release requires what?

Answer 2

a change in protein conformation
(Ex: Bumps for EP dissociating to E + P, with bump indicating that there is a change in conf taking place)

Question 3

Amino Acid motions

Answer 3

referring to their side chain moving

Question 4

what are amino acid side chain motions correlated with?

Answer 4

they are correlated with and biased for certain conformations (POPULATION MODEL)
- also correlated with certain mechanism changes, and so they are biased for those
Ex: S binds in a certain way then twists to be in a certain conf, the E must have a change in conf to help that twisting occur. Once S is bound, now a biased conformation

Question 5

conformation selection model

Answer 5

part of population shift.
- S binding does not impose a change in conf
- instead S binds to E in a conf similar to ES and then will select for that conformation
- and then this conformation will be stabilized to shift more E to this conf in order to bind ligands better

• S is released if E conformation is incompatible with ES

Question 6

key concept behind the conformational selection

Answer 6

• network of amino acids that are going to be involved