New evidence for glutamic acid as an iron ligand in hemerythrin

Abstract

The amino acid sequence of the respiratory protein, hemerythrin, from Phascolopsis gouldii was reinvestigated in the region of residue 58. Sequenator analyses were performed on peptide 50–113, obtained by trypsin digestion of the intact protein, and on peptide 50–62, obtained by cyanogen bromide cleavage of peptide 50–113. In both peptides residue 58 was unambiguously identified as glutamic acid and residue 59 as glutamine. This corrects a previous mistake in the assignment of residue 58 and makes its proposed role as an iron ligand more plausible.