Peptides word origin

Ions derived from the N-terminus of the original peptide are termed a, b, or c (in other words, the charge is retained on the N-terminus), while those originating from the C-terminus are named x, y, or z. Numerical subscripts contain information on the number of amino acid residues present in a given ion. It must be remembered that we are interested only in charged species since the neutral ones are not detected and do not yield peaks in the spectrum. The main idea behind this system is shown in Fig. 6.5, and the structures of selected ion types are depicted in Fig. 6.6. 

Our historical account would be incomplete without a few words about the surprisingly original four center condensation (4CC) method of Ivar Ugi [60]. The reaction of an acylamino acid, or peptide with an amine, an aldehyde and an isonitrile leads to a peptide derivative... 

This name originated from the Filipino word antokin which means sleepy, due to the sleeper activity of these peptides (Jimenez, 2009). 

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