Investigation of newly synthesized endothelin peptides by high-performance liquid chromatography coupled to electrospray mass spectrometry

A number of newly synthesized endothelin peptides have been examined by high performance liquid chromatography/electrospray mass spectrometry (HPLC/ES-MS). The presented data allowed reliable identification of both the target peptides and a number of associated side products including the target peptide in methylated form and peptide sequences with relative molecular masses lower than those desired. Characteristic fragments in the ES mass spectra permitted differentiation between the methylation sites involving the carboxylic functions of the C-terminus and the side-chain of the aspartic acid.