Figure 4
From: The proteome of the calcified layer organic matrix of turkey (Meleagris gallopavo) eggshell
Spectrum of a turkey OC-116 peptide indicating the presence of a C-terminus similar to chicken OC-116. This peptide was not found in turkey OC-117 but matches the chicken OC-116 C-terminus (aa671-682), which is missing in the turkey protein. This quadruply charged peptide was identified with a posterior error probability (PEP) of 0.0005 and a mass error of −0.144 ppm. It is the only evidence for the presence in the turkey protein of a C-terminus similar to that of chicken OC-116. The N-terminal glutamine was cyclized to pyroglutamate during peptide fractionation under acidic conditions, a frequently observed modification of peptides with N-terminal glutamine.