Perissodactyla: Die Primärstruktur der Hämoglobine eines Flachlandtapirs(Tapirus terrestris):Glutaminsäure in Position 2 der β-Ketten

Abstract

The Hb from a lowland tapir (Tapirus terrestris) were analyzed and the complete primary structure is described. The globin chains were separated on CM cellulose column in 8 M urea and the amino-acid sequences were determined in the liquid phase sequenator. Globin consists of 2 .alpha. chains (.alpha.I and .alpha.II) and .beta. major and .beta. minor components. The .alpha. chains differ only at 1 position: .alpha.I contains Asp and .alpha.II Gly. The .beta. chains are heterogeneous: Asp and Glu are at positions .beta.21 and .beta.73 of the .beta. major components and Asn and Ser at position .beta.139. In the .beta. minor components 4 positions had more than 1 amino acid, namely .beta.2, .beta.4, .beta.6 and .beta.56. The sequences are compared with those of man, horse and rhinoceros. Four residues of horse metHb, which are involved in the .alpha.1.beta.1 contacts are substituted in tapir Hb. In the .alpha. chains: .alpha.107(G14) Ser .fwdarw. Val, .alpha.111(G18) Val .fwdarw. Leu, .alpha.115 (GH3) Asn .fwdarw. Asp or Gly; in the .beta. chains: .beta.116(G18) Arg .fwdarw. Gln. The amino acid at .beta.2 of the major components is Glu while Gln and His are in the minor components. Although Glu, a binding site for ATP, does not interact with 2,3-bisphosphoglycerate, Gln and His in the minor components are responsible for the slight effect of 2,3-bisphosphoglycerate on tapir Hb.