Add time:08/03/2019         Source:sciencedirect.com

In collision-induced dissociation (CID) experiments of peptides, the formation of c- and z-ions originating from NCα bond cleavage of the peptide backbone is unusual, whereas b- and y-ions are often observed in positive-ion CID spectra. Here we report that characteristic product c- and z-ions can be observed in negative-ion CID spectra of peptides with Asp and Asn residues. The negative c- and z-ions are mainly generated at the NCα bond of Xxx-Asp and Xxx-Asn residues that are classified as the flexible amino acids in protein chemistry. In the absence of any acidic amino acid residues, negative-ion CID spectra show dominant c-ion peaks originating from cleavage at the NCα bond lying in between the 3rd and 4th residues from the C-terminus of analyte peptides. It is proposed that the NCα bond cleavage leading to the formation of c- and/or z-ions is caused by the negative charge located on the amide nitrogen, which generated with an intra-molecular hydrogen abstraction from the backbone amide regions due to negative-charged acidic functional groups.

We also recommend Trading Suppliers and Manufacturers of Z-D-ARG(Z)2-OH (cas 104321-57-5). Pls Click Website Link as below: cas 104321-57-5 suppliers