Primary structure of ?-globin chains from river buffalo (Bubalus bubalis) hemoglobin.

Primary structure analysis of the four river buffalo a-globin chains showed that haplotypes A and B differ from each other by a substitution at codon 64 that may encode Ala or Asn. The A haplotype encodes two a-globin chains, Ia1 and IIa3, which differ at positions 129 and 131: Ia1 has 64 Ala, 129 Phe, 131 Asn; IIa3 has 64 Ala, 129 Leu, 131 Ser. The B haplotype encodes two a-globin chains, Ia2 and IIa4, which differ at positions 10 and 11: Ia2 has 10 Ile, 11 Gln, 64 Asn; IIa4 has 10 Val, 11 Lys, 64 Asn. Apart from the Ala/Asn polymorphism at position 64, amino acid substitutions in allelic and nonallelic a-globin chains seem to have arisen by single point mutations. Detection of electrophoretically silent mutations due to neutral amino acid substitutions and their influence on the isoelectric point are discussed. Furthermore, primary structures of river buffalo a-globin chains are compared to other species of the Bovidae family to suggest evolutionary events that have characterized the amino acid substitutions of river buffalo hemoglobin.