Open AccessAmino acid sequence of the monomer subunit of the giant multisubunit hemoglobin from the earthworm Pheretima sieboldi
Author(s) -
SUZUKI Tomohiko
Publication year - 1989
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1989.tb15092.x
Subject(s) - heme , chemistry , peptide sequence , amino acid , cysteine , hemoglobin , biochemistry , trimer , lumbricus terrestris , cystine , stereochemistry , biology , earthworm , enzyme , dimer , organic chemistry , gene , paleontology
The giant extracellular hemoglobin of the earthworm Pheretima sieboldi is mainly composed of two hemecontaining subunits: a monomer; chain I and a disulfide‐bonded trimer of chains II, III and IV. Both subunits can be separated easily by gel filtration under alkaline conditions. The amino acid sequence of chain I has been determined. It is composed of 141 residues, has two half‐cystine residues forming a intrachain disulfide bridge, and has a molecular mass of 16911 Da including a heme group. Heterogeneity was found at position 37 (His or Ser). The amino acid sequence of Pheretima chain I showed 30–50% identity with those of eight heme‐containing chains of Lumbricus and Tylorrhynchus hemoglobins. The sequences of nine chains of annelid giant hemoglobins were comparéd separately in the functionally essential central exonic region and structurally essential side exonic regions, and a phylogenetic tree was constructed. The amino acid substitution rate for the central exon was found to be about 1.5 times slower than that for the side exons.