Furuta H, Ohe M, Kajita A
J Biochem. 1977 Dec;82(6):1723-30. doi: 10.1093/oxfordjournals.jbchem.a131870.
Intracellular hemoglobins of the sea blood clam Anadara broughtonii consist of HbI dimer (33%) and HbII tetramer (60%). The molecular weights of globins of HbI and HbII were determined by sodium dodecyl sulfate (SDS)-gel electrophoresis to be 15,500 and 16,500, respectively. The existence of two dissimilar chains, alpha and beta, in globin from HbII tetramer was confirmed electrophoretically and the chains were separated by CM-cellulose chromatography in 8 M urea. In contrast, globin from HbI dimer showed a single band on two types of electrophoresis. The NH2-terminus and the COOH-terminus of HbI were determined to be proline and leucine, respectively. From the results of finger-printing, the alpha and beta chains from HbII were considered to have a rather similar profile, whereas globin from HbI was very different. The results obtained by amino acid analysis of each chain also supported the above findings. It was thus shown that HbII has an alpha2beta2 subunit structure, which is rare among invertebrate hemoglobins. On the other hand, HbI seems to have two identical subunits, designated as "gamma", and to exist as a "gamma2" dimer structure. Both Anadara Hb's appear to have no functional groups relating to the Bohr effect and to be unable to form a binding site for organic phosphates.
海血蛤（Anadara broughtonii）的细胞内血红蛋白由HbI二聚体（33%）和HbII四聚体（60%）组成。通过十二烷基硫酸钠（SDS）-凝胶电泳测定，HbI和HbII珠蛋白的分子量分别为15,500和16,500。通过电泳证实了HbII四聚体的珠蛋白中存在α和β两条不同的链，并在8M尿素中通过CM-纤维素色谱法将这两条链分离。相比之下，HbI二聚体的珠蛋白在两种电泳中均显示出一条带。测定HbI的NH2末端和COOH末端分别为脯氨酸和亮氨酸。从指纹图谱结果来看，HbII的α链和β链的图谱较为相似，而HbI的珠蛋白则非常不同。对每条链进行氨基酸分析所得结果也支持上述发现。由此表明，HbII具有α2β2亚基结构，这在无脊椎动物血红蛋白中较为罕见。另一方面，HbI似乎具有两个相同的亚基，命名为“γ”，并以“γ2”二聚体结构存在。两种海血蛤血红蛋白似乎都没有与玻尔效应相关的官能团，也无法形成有机磷酸盐的结合位点。
