Non-heme protein in the giant extracellular hemoglobin of the earthworm Lumbricus terrestris.
AUTOR(ES)
Fushitani, K
RESUMO
The protein/heme mass ratio for the extracellular hemoglobin of the earthworm Lumbricus terrestris has been redetermined. We find a value of 19,000 g of protein per mol of heme. Four major, heme-containing chains (a, b, c, and d), present in equal proportions, have a total molecular mass, with four hemes, of 69,664 Da based on their sequences. The intact hemoglobin comprises 12 subunits that form a two-layered hexagonal structure of about 3.8 MDa. This value, together with our determination of the protein/heme ratio, requires that 4 abcd units are present in each 1/12th subunit and that 192 heme-containing chains are present in the hemoglobin molecule. Our data indicate that approximately 2200 g of non-heme protein is present for each mole of heme-containing chain, or about 35,200 g per 1/12th subunit. This conclusion is consistent with the observation that chains of 31-37 kDa are present. On this basis the intact molecule would have 12 non-heme chains and 204 chains in all to give a total molecular mass of 3.77 MDa, close to that observed.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=282772Documentos Relacionados
- Bracelet protein: a quaternary structure proposed for the giant extracellular hemoglobin of Lumbricus terrestris.
- Non-heme iron enzymes: Contrasts to heme catalysis
- Non-heme iron protein: A potential target of nitric oxide in acute cardiac allograft rejection
- Scanning transmission electron microscopic examination of the hexagonal bilayer structures formed by the reassociation of three of the four subunits of the extracellular hemoglobin of Lumbricus terrestris.
- IDENTIFICATION BY ISOTOPIC SUBSTITUTION OF THE EPR SIGNAL AT g = 1.94 IN A NON-HEME IRON PROTEIN FROM AZOTOBACTER*