Die Primärstruktur des Hämoglobins vom Breitmaulnashorn (Ceratotherium simum,Perissodactyla):β2 Glu

Abstract

The Hb from a white rhinoceros (C. simum) was analyzed and the complete primary structure of the .alpha. and .beta. chains is described. The globin chains were separated on CM-cellulose column in 8 M urea buffer. The amino acid sequences were mainly determined by automatic degradation of tryptic peptides in the sequenator. Globin consists of 1 .alpha.- and several .beta.-chain types. The .beta. chains differ at position .beta.62 where the amino acids threonine, serine and alanine were identified and at position .beta.116 where glutamine or lysine were found. The sequences are compared with those of horse, wild ass and zebra Hb. Five amino acid residues of horse Hb, which are involved in the .alpha.1.beta.1 contacts are substituted in white rhinoceros Hb. These substitutions are .alpha.35 Gly .fwdarw. Ser, .alpha.107 Ser .fwdarw. Val, .alpha.111 Val .fwdarw. Leu, .alpha.115 Asn .fwdarw. Gln and .beta.116 Arg .fwdarw. Gln or Lys. Furthermore glutamic acid was found at position .beta.2 of rhinoceros Hb. In most mammalian Hb the amino acid at this position is histidine, which is one of the residues that binds, 2,3-bisphosphoglycerate in deoxyhemoglobin. In this way 2,3-bisphosphoglycerate controls the O2 affinity of Hb.