Open AccessAmino acid sequence of the monomer subunit of the giant extracellular hemoglobin of the aquatic oligochaete, Tubifex tubifex
Author(s) -
STERN Mary S.,
VINOGRADOV Serge N.,
SHARMA Pawan K.,
EREIFEJ Khalil,
WALZ Daniel A.
Publication year - 1990
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1990.tb19428.x
Subject(s) - tubifex tubifex , tubifex , globin , lumbricus terrestris , peptide sequence , biochemistry , cysteine , protein subunit , hemoglobin , amino acid , biology , monomer , trimer , chemistry , stereochemistry , dimer , gene , enzyme , organic chemistry , earthworm , polymer , paleontology , fishery , ecology
The extracellular hemoglobin of the aquatic oligochaete Tubifex tubifex consists of four subunits: a monomer of 16.5 kDa, a disulfide‐bonded trimer of about 50 kDa and at least two subunits of about 30 kDa. The complete amino acid sequence of the monomeric subunit was determined: it consists of 141 amino acid residues and has a molecular mass of 16286 Da including a heme group. 39 residues (28%) were found to be identical with those in the corresponding positions in the monomeric globin chains from Lumbricus terrestris, Pheretima sieboldi , and Tylorrhynchus heterochaetus . Tubifex and Lumbricus are most similar, with 75 amino acid identities (53%). There are eight invariant residues amongst these monomeric globins and the intracellular monomeric globin of Glycera and the human β‐globin. The monomeric globin from Tubifex aligns best with those of group A, globins which have a Cys in their second position and an invariant Lys‐Val‐Lys at positions 9–11 [Gotoh et al. (1987) Biochem. J. 241 , 441–445]. The two cysteine residues, at positions 2 and 131, appear to be disulfide‐bonded.