一种软体动物（三角帆蚌）细胞外血红蛋白的四级结构。
The quaternary structure of a molluscan (Helisoma trivolvis) extracellular hemoglobin.
作者信息
Terwilliger N B, Terwilliger R C, Schabtach E
出版信息
Biochim Biophys Acta. 1976 Nov 26;453(1):101-10. doi: 10.1016/0005-2795(76)90254-3.
The hemoglobin (erythrocruorin) of the planorbid mollusc Helisoma trivolvis has a molecular weight of 1.7-10(6) and a sedimentation coefficient (s0 20, w) of 33.8 S at pH 7.0. At pH 2.0, the pigment consists of 32 S and 13 S material. The hemoglobin exists as a 350 000 molecular weight submultiple in 6 M guanidine and can be further dissociated into a 175-200 000 dalton polypeptide in 6M guanidine, 0.1 M 2-mercaptoethanol or by sodium dodecyl sulfate gel electrophoresis of globin, performic acid oxidized globin or carboxymethylated globin. Electron microscope observations show a ten-membered ring structure measuring 200 A in diameter. It is proposed that Helisoma hemoglobin consists of a 1.7-10(6) dalton circular assembly of ten 175-200 000 dalton polypeptide chains. The amino acid composition of the pigment is reported. The hemoglobin contains one heme per 18-19 000 g protein. Limited proteolysis of the intact pigment shows 60 000, 40 000 and 17 000-18 500 dalton components when analyzed by sodium dodecylsulfate gel electrophoresis. It is likely that the 175-200 000 dalton polypeptide consists of a linear arrangement of 8-12 heme-containing domains, each domain having a molecular weight of 18-19 000.
椎实螺属软体动物——三旋膀胱螺的血红蛋白（红血球素）分子量为1.7×10⁶，在pH 7.0时沉降系数（s₀₂₀,w）为33.8 S。在pH 2.0时，该色素由32 S和13 S的物质组成。血红蛋白在6 M胍中以分子量为350 000的亚倍数形式存在，并且在6 M胍、0.1 M 2-巯基乙醇中或通过对珠蛋白、过甲酸氧化珠蛋白或羧甲基化珠蛋白进行十二烷基硫酸钠凝胶电泳，可进一步解离为175 - 200 000道尔顿的多肽。电子显微镜观察显示其为直径200 Å的十元环结构。有人提出，三旋膀胱螺血红蛋白由十条175 - 200 000道尔顿多肽链组成的1.7×10⁶道尔顿环状聚集体构成。文中报道了该色素的氨基酸组成。血红蛋白每18 - 19 000 g蛋白质含有一个血红素。对完整色素进行有限的蛋白酶解后，通过十二烷基硫酸钠凝胶电泳分析显示有60 000、40 000以及17 000 - 18 500道尔顿的组分。175 - 200 000道尔顿的多肽可能由8 - 12个含血红素结构域线性排列组成，每个结构域分子量为18 - 19 000。
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