Question about Phosphoglycerate mutase (PGM) mechanism

[Raphael Chaleil]

Davit Hakobyan wrote:
> Hi All,
> 
> In glycolysis the phosphoglycerate mutase (PGM) converts 3PG into 2PG.
> As it appears the phosphorylated HIS residue (8) "gives" its PO3 to
> 3PG and some B element (probably Boron) takes the Hydrogen atom, which
> have been previously bound to the oxygen of the second carbon (C2). My
> question is what is this B element, which takes the hydrogen ?
> Is it really a Boron ? Because I have couple yeast PGMs (downloaded
> from Protein Data Bank site) and they do not have any Boron atom.
> The PGM i'm interested the most has its ID 1QHF at PDB (and no Boron
> (B) atom).
> 
> Thanks for any help.
I suppose B stands for a basic group as proton acceptor, nothing to do 
with Boron.

Regards