The structures are OK except to check the R-group of lysine and valine (the lys R-group should have four carbons and the val R-group should have only three carbons). The overall charge of the phosphopeptide is correct if both OH groups of the phosphate group are completely dissociated at pH 7.4. The first one certainly is, but I do not have a Ka2 value handy to check to what degree the second hydrogen is dissociated (using the Henderson-Hasselbalch equation). But it seems reasonable to approximate that at this pH it is essentially in completely dissociated form also, giving the phosphate group an overall charge of -2 And as you said, with opposite overall charges of +1 and -1, the peptide and phosphopeptide would migrate in opposite directions in an electrophoresis gel.
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