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M. Stoeckelhuber, T. Gorr, T. Kleinschmidt
The Primary Structure of Three Hemoglobin Chains from the Indigo Snake (Drymarchon corais erebennus, Serpentes): First Evidence for ?D Chains and Two ? Chain Types in Snakes
The hemoglobin of the indigo snake (Drymarchon corais erebennus, Colubrinae) consists of two components, HbA and HbD, in the ratio of 1:1. They differ in both their ? and ? chains. The amino acid sequences of both ? chains (?A and ?D) and one ? chain (?I) were determined. The presence of an ?Dchain in a snake hemoglobin is described for the first time. A comparison of all snake ? chain sequences revealed the existence of two paralogous ? chain types in snakes as well, which are designated as ?I and ?II type. For the discussion of the physiological properties of Drymarchon hemoglobin, the sequences were compared with those of the human ? and ? chains and those of the closely related water snake Liophis miliaris where functional data are available. Among the heme contacts, the substitution ?D58(E7)His->Gln is unusual but most likely without any effect. The residues responsible for the main part of the Bohr effect are the same as in mammalian hemoglobins. In each of the three globin chains only two residues at positions involved in the ?1/_2 interface contacts, most important for the stability and the properties of the hemoglobin molecule, are substituted with regard to human hemoglobin. On the contrary, nine, eleven, and six ?1/?1 contact residues are replaced in the ?A, ?D, ?I chains, respectively.
Biological Chemistry, Walter de Gruyter
Print ISSN: 1431-6730
Volume: 383, 12/2002
Pages: 1907 - 1916