Possible Mechanism for this reaction

[Overbearingminds]

To make a long story short E1 (a protein) reacts with Ubiquitin (another protein) and covalently bonds via a cysteine residue....what type of reaction mechanism are we looking at here? The reaction is ATP dependent if it helps.

 

Thanks a lot in advance.

[Horza2002]

The ubiquitin has a carboxylic acid which is activated by ATP with a Mg2+ ion that helps activate the molecule. The activated phosphoester is attacked by the thiol of the E1 enzyme. As far as I can see, thats what you've asked for.

 

http://en.wikipedia.org/wiki/Ubiquitin

 

There is alot of information on this webpage about the mechanisms if you want.

ubiq.pdf

[Overbearingminds]

Perfect! Just what I needed to know! Thanks Horza

[Horza2002]

No problemo. Im not 100% sure of the mechanism, however thioester bonds are normally formed in this manor (i.e. in polyketide synthase enzymes)

[hypervalent_iodine]

Checked out your mechanism, Horza. It seems perfectly logical to me!