[The primary structure of the hemoglobin from a white rhinoceros (Ceratotherium simum, perissodactyla): beta 2 Glu].

The hemoglobin from a white rhinoceros (Ceratotherium simum) was analysed and the complete primary structure of the alpha and beta chains is described. The globin chains were separated on CM-cellulose column in 8M urea buffer. The amino acid sequences were mainly determined by automatic degradation of tryptic peptides in the sequenator. The results show, that globin consists of one 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 hemoglobin. Five amino acid residues of horse hemoglobin, which are involved in the alpha 1 beta 1 contacts are substituted in white rhinoceros hemoglobin. These substitutions are alpha 35 Gly leads to Ser, alpha 107 Ser leads to Val, alpha 111 Val leads to Leu, alpha 115 Asn leads to Gln and beta 116 Arg leads to Gln or Lys. Furthermore glutamic acid was found at position beta 2 of rhinoceros hemoglobin. In most mammalian hemoglobins the amino acid at this position is histidin which is one of the residues that binds, 2,3-bisphosphoglycerat in deoxyhemoglobin. In this way 2,3-bisphosphoglycerat controls the oxygen affinity of hemoglobin.