Amino acid sequence of the monomer subunit of the extracellular hemoglobin of the earthworm, Pheretima hilgendorfi.

The complete amino acid sequence of the monomer subunit of Pheretima hilgendorfi hemoglobin was determined: It consists of 140 amino acid residues, including a disulfide bond but no methionine, and has a molecular weight of 16,107 Da. Using computed analyses (amino acid maximum homology) with known sequences of monomer subunits of earthworm's hemoglobins, 115 (82%) were found to be identical with those in the corresponding positions of chain I (monomer subunit) of Pheretima sieboldi hemoglobin; 81 residues (55%), 71 residues (47%), and 66 residues (43%) were found to be in identical positions of the sequences of chain I of Lumbricus terrestris hemoglobin, chain I of Tubifex tubifex hemoglobin and chain I of Tylorrhynchus heterochaetus hemoglobin. Orthologous sequence data of monomer globins that belong to the strain A of annelid hemoglobins are discussed as useful clues for investigation of the divergence pattern of Pheretima species.