Calcium and GTP

[Dima Klenchin]

In article <3450F271.41C6 at bloom.aecom.yu.edu>, Philip Aisen <aisen at bloom.aecom.yu.edu> wrote:
:When we add 30mM calcium chloride to 5mM GTP in Mg/EGTA/sucrose/PIPES
:buffer, pH 7.4, a heavy white ppt. develops.  No precipitate develops
:with ATP under similar circumstances.  No free phosphate is evident by
:NMR spectroscopy.  
:
:Does anyone have an explanation?
:
:Thanks.
:
:Philip Aisen

Ca salt GTP is much less soluble than Ca salt ATP. Simple look at 
molecular formulas make it clear why.

Ca salts of all nucleotides are less soluble than Mg salts.

- Dima