Rapid primary structure determination of myoglobins by a complementary approach based on mass spectrometry and Edman degradation

The primary structure of two myoglobins (Mbs), isolated from the heart and muscle of Equus asinus L. and Struthio camelus L., respectively, was determined using a combined approach based on Edman degradation and mass spectrometry. The strategy allowed the determination of donkey Mb sequence, which was found to be identical to the horse Mb, as also confirmed by ESI/Q-TOF mass spectrometry. Indeed, donkey Mb accurate molecular mass (16951.50 Da) was in good agreement with the molecular mass of horse Mb (16951.48 Da). A similar strategy was also applied for revisiting the primary structure of ostrich Mb, revealing the presence of two amino acid substitutions (i.e. Asp53Glu and Asp60Glu), with respect to the previously reported sequence ( Enoki, Ohga, Ishidate, & Morimoto, 2008). The proposed approach represents a rapid and reliable tool for determining/revisiting the primary structures of the highly conserved myoglobins.