E1's Proton Wire

Question 1

Proton in step 2 of Rxn 1(catalyzed by E1)

Answer 1

Proton is added, also gets lost in step 5.

• Must be able to deliver the proton,.. something at the end must be delivered back early on.
• Red box diagram = this is where the proton wire is (10 acidic AA passing H+ back and forth)

Steps 2 and 5 MUST occur OUT of phase. One must be occuring at the same time, but one must be getting deprotonated and the other getitng protonated in order to be able to pass H+ back and forth.

Arrows point to special loops ordering and disordering. These loops control which rxn is occurring at which time (control out of phaseness)

Question 2

Proton wire

Answer 2

proton hopping mechanism that goes in a very speific direction/directions.

Proton wire in E1 is connecting two active sites. The active site that is finishing a rxn sequence of Rxns 1 and 2 with the AS that is beginning the rxn sequence of rxns 1 and 2.

Question 3

Each TPP is bound where?

Answer 3

Each TPP bound between N terminus of alpha and beta subunits at the end of a water filled tunnel.

This tunnel is where the wire will be happening. As one is finishing, a proton is being transferring to help with the other progressing forward.

These WILL NOT MOVE, it is the proton that moves between the active sites.

Question 4

AA present in proton wire?

Answer 4

(10 acidic , deprotonated so you can pass H+) Asp or Glu are both present, these are what link the two active sitres of the proton wire to help transfer the H+

Question 5

Diff between wire and hop?

Answer 5

A wire is a subset of a hop, a hop can be random or specific, in this case is specific.

Question 6

WHat moves into this proton wire?

Answer 6

E2’s lipoamide (lipolysl) arm moves in to do rxn