Hello folks, I would like to measure the concentrations of proteins containing phosphotyrosines using absorbance at 280nm.
I'm wondering about calculating extinction coefficients by the Edelhoch method - as used in ProtParam for example: http://web.expasy.org/protparam/protparam-doc.html Given that phosphotyrosine absorbs less strongly at 280nm than tyrosine, has anyone developed a modified extinction coefficient calculation that treats tyrosine and phosphotyrosine separately and has the same kind of accuracy that Edelhof achieved using amino acid analogues (e.g. comparing glycyl-L-tyrosylglycine to the phophorylated equivalent)? Cheers, Will.
