ISSN:
0030-493X
Keywords:
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
We have been able to extend the use of Schiff base derivatives in peptide sequencing to N-terminal prolyl peptides. Earlier studies from this laboratory revealed that certain aromatic Schiff bases of peptide esters gave electron-impact mass spectra with relatively intense molecular, sequence and internal fragment ions. We observed that the reaction of N-terminal prolyl peptide esters with 4-dimethylaminonaphthaldehyde, p-dimethylaminobenzaldehyde and 2-pyridinecarboxaldehyde gave cyclization products which were found to be 2-substituted-1-keto-3-aryl-5H-imidazo-[1,5-a]-pyrrole derivatives. The molecular ion and many of the expected cleavages were prominent in the mass spectra. Deuterium labeling at the α-carbon, amide nitrogen, or other exchangeable positions has been used in assigning the structure. It was also confirmed by the fragmentation pattern of the products derived by permethylation of the peptide derivative with tetramethylammonium hydroxide. Comparable cleavage patterns were seen among the N-terminal prolyl peptides examined. Proline amide gave the corresponding cyclized product. With the inclusion of N-terminal prolyl peptides in the list of peptides that we have examined, we may now prepare volatile derivatives of peptides containing any of the protein amino acids in two steps: esterification and treatment with the appropriate aromatic aldehyde.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/oms.1210090209
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