中国産アオゴカイPerinereis aibuhitensisと徳島産イトメTylorrhynchus heterochaetusの血液に浮遊する巨大ヘモグロビンのグロビン鎖の一次構造比較

Amino acid sequences of four types of globin chains a, A, b, and B of the giant Hb from the polychaete Perinereis aibuhitensis, which were collected at the delta of the Yangtze River in the People's Republic of China, were determined by the combination of Edman degradation and RT-PCR method. The primary structures of Perinereis globin chains are compared with those of globins isolated from the polychaete Tylorrhynchus heterochaetus which was collected at the delta of the River Yoshinogawa in Tokushima City. Perinereis globin chains appeared to have 140 amino acid residues for the chain a, 144 for A, 147 for b and B, respectively. These sequences were completely in agreement with the partial cDNA sequences by RT-PCR which covered 119～137 amino acid residues. Some heterogeneities were found for the chain A by protein sequencing. On the other hand, RT-PCR revealed a few polymorphisms in the sequences of chains a, A and b. According to the phylogenetic tree constructed by UPGMA method, Perinereis globin chains were appeared to be separated into two strains A and B at the time later than the separation of vertebrate Mb and Hb but earlier than the separation of the alpha and beta chains of vertebrate Hb. Perinereis globins b and B appeared to be separated from globin A after the time when the trimeric globin chains A, b, and B had been separated clearly from the derivative of globin a according to the phylogenetic tree constructed by NJ method. The homologies between the corresponding globin chains of Perinereis and Tylorrhynchus Hbs were estimated to be within the range of 48～84%.