The quarternary structure of an unusual high-molecular-weight intracellular haemoglobin from the bivalve mollusc Barbatia reeveana

Abstract

The arcid clam Barbatia reeveana contains an intracellular haemoglobin with an unusual structure. First, compared with other intracellular haemoglobins, it is extremely large, with a mol.wt. of 430000 and an s20,w of 13.6S. A minor component (mol.wt. = 220000; s2O,w = 9.7S) is also present as a probable dissociation product of the major component. Secondly, this haemoglobin has an unusual subunit structure. It contains 1 mol of haem per 16000 g of protein, in common with most other haemoglobins. However, the smallest polypeptide that could be obtained after treatment with sodium dodecyl sulphate or 6 M-guanidine with reducing agent has a mol.wt. of 32000-37000. Digestion of the haemoglobin with the proteinase subtilisin produces both 57000-and 30000-mol.wt. aggregates that contain 1 mol of haem per 16000 g of protein and that can be dissociated into 16 500-mol.wt. polypeptides by treatment with sodium dodecyl sulphate. The intact polymer shows slight co-operativity (h = 1.7), lacks a Bohr effect between pH 7 and 8, and has a low oxygen affinity [P50 = 4.8 kPa (36mmHg) at 200C] relative to other haemoglobins. The 30000-mol.wt. aggregate obtained by digestion of the polymer binds oxygen reversibly with an affinity greater than that of the polymer, but with some co-operativity (h = 1.7). These results are consistent with the hypothesis that the subunits of this unusually large intracellular haemoglobin are 32000-mol.wt. polypeptides that in turn are composed of two covalently linked haem-containing oxygen-binding domains. This is the first report of an intracellular haemoglobin with such a structure.Most intracellular haemoglobins of both vertebrates and invertebrates consist of haem-containing polypeptides with mol

Haematological characteristics of the Bloody cockle <i>anadara senilis</i> (L.) from Andoni flats, Niger Delta, Nigeria.

“…For example, Jawad et al, (2004), found that the values of Hb, RBC and PCV increased as the fish size increase. Similar result were obtained for Clarias batrachus (Jushi & Tardon, 1977), Tilapia zilli (Ezzat et al, 1973), Cyprinus Carpio, bivalve Barlatia reevena (Grinich & Terwilliger, 1980) and Amphiprous cuchia (Banerjee, 1986). It should be noted that the differences recorded in blood parameters between various sizes according to Paizada et al, (1983), are genetically determined, but Chaudhuri et al, (1986) suggested that the difference might be due to the higher metabolic rate, of the bigger fish compared to smaller ones.…”

Characterisation of Duplicated Haemoglobin Genes in Bivalves

“…Moreover, from results in this study, globins present in the haemolymph of A. trapezia do not seem to show a Bohr effect unlike Hbs found in teleost fish species (Souza & Bonilla-Rodiguez, 2007;Witeska, 2013). The saturation of oxygen appears independent of pH as a significant drop in pH is coupled with a significant increase in sO 2 % for animals exposed to air for 12 h. This is consistent with previous studies on Hb containing bivalves such as Barbatia reeveeana (Grinich & Terwilliger, 1980), Cardita floridana (Manwell, 1963) and Anadara broughtonii (Furuta & Kajita, 1983) for which no Bohr effect was observed.…”

“…Circulating Hbs may also be found within erythrocytes (intracellular) or freely dissolved in fluid tissue such as blood or haemolymph (extracellular) (Ching Ming Chung & Ellerton, 1980). Extracellular Hbs are extremely diverse in subunit size and quaternary structure, however, they all share the same globin fold as intracellular Hbs (Negrisolo et al, 2001 (Grinich & Terwilliger, 1980). Other examples of structural variation include annelid species, such as Riftia pachyptila and Lumbricus terrestris, which possess Hbs consisting of 24 and 144 subunits respectively (Royer et al, 2000;Strand et al, 2004;Flores et al, 2005).…”

“…These erythrocytes contain multiple Hbs; which are often dimeric (~ 32 kDa) and tetrameric (~ 65 kDa) (Como & Thompson, 1980b;Furuta & Kajita, 1983;Suzuki et al, 2000), with the exception of a 430 kDa polymeric Hb found in some members of the Barbatia genus, such as B. reeveana and B. lima (Grinich & Terwilliger, 1980;Suzuki & Arita, 1995). Dimeric Hbs in the Arcidae exhibit further structural complexity and can be homo-dimeric or hetero-dimeric (Furuta & Kajita, 1983;Mann et al, 1986;Suzuki et al, 1992).…”

Origin of a "bridge" intron in the gene for a two-domain globin.

“…Red cells of the clam Barbatia reeveana have hemoglobins with two-domain chains and others composed of singledomain chains (25,26). The cDNA-derived amino acid sequence of 308 residues of the two-domain globin (27,28) shows that two very similar domains (78% identical) are connected by two lysine residues (Fig.…”