For a few hundred microlitres of 100-500uM WT RAS:

Add 10 mM EDTA, 1-2 uL of CIP and a 10 fold excess of GPPNHp.

Incubate at 37C for 10 mins.

Add MgCl2 to a final concentration of 20 mM MgCl2 and keep on ice.

You can then either dialyze or put through a size exclusion column to get rid of the extra nucleotide and EDTA.

Hi Ryan,

Thanks for answering this question. Can you tell me what is CIP and why it is used for GTP labelling. Also will desalting columns(Zeba spin ) do the work instead of dialysis to remove the extra nucleotide.

CIP means Calf Intestinal Phosphatase