GDP_pKa_Query

[CoffeeIsTheColour]

Hi all,

Generally, I was wondering what the pka of GDP is? In particular, I'm interested in the state of it in the cell, i.e pH ~7.4.

I found this...pKa - <1
2.9
6.3
9.6

I would assume that these are the corresponding pKa's while progressively deprotonating the molecule, so <1 corresponds to all 3 OH groups being protonated and 9.6 corresponds to all 3 OH groups deprotonated.

Is this about right?

If so, then it would make sense that at pH 7.4 there would be one OH phosphate group protonated. Is this right? Then if so, which one, alpha or beta phosphate?

Many thanx,

M

[JackBean]

I guess it is better to have one charge on two groups rather then two charges on one group and the other uncharged...