Isomeric peptides distinguishing

This method is quite useful when distinguishing isomeric peptides, i.e., with the same amino acids but in a different sequence (Fig. 65). a, AcN-Val-Ala-Leu-COOMe b, AcN-Leu-Ala-Val-COOMe. 

The differentiation between isomeric leucine and isoleucine has long been a problem in mass spectrometric peptide sequencing. However, a simple method has been developed, employing leucine containing a non-labile isotopic label, to distinguish between these two amino acids 67). The... 

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