I have been using a synthetic peptide (nh2) RVYIHPFHL (cooh) in a reaction mixture which contains .2M Na+Po4 and have been unable to dialyze the sodium out or exchange it with K+.
I always get a 100% modified peptide with + 22 when glucose is added to the mixture and only a small amount of the +22 adduct when no glucose is in the mixture . I have been using alpha-cyano as a matrix and have heard it may contain sodium but the extent of sodium modification of the peptide without glucose is far less than with glucose . I was wondering does anyone know of a sure way to displace the Na+ to allow us to be sure it is a sodium adduct (unfortunately we can not run the reaction without sodium it must be removed afterwards). Thanks for any help,
Bart Haigh
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