The hemocyanin of the bivalve, Yoldia limatula (Say) was found by light-scattering to have a mol. wt of 8.0 +/- 0.6 x 10(6). Mass measurements by scanning transmission electron microscopy (STEM) gave a particle mass of 8.25 +/- 0.42 x 10(6) for the native particle and 4.09 +/- 0.20 x 10(6) for the half-molecule. 2. The hemocyanin subunits fully dissociated in 8.0 M urea and 6.0 M GdmCl at pH 8.0, and at pH 11.0, 0.01 M EDTA have mol. wts of 4.38 x 10(5), 4.22 x 10(5) and 4.71 x 10(5), close to one-twentieth of the parent molecular weight of Y. limatula hemocyanin and most gastropod hemocyanins. 3. Analyses of the urea dissociation transitions studied at pH 8.0, 1 x 10(-2) M Mg2+, 1 x 10(-2) M Ca2+ and pH 8.0, 3 x 10(-3) M Ca2+ suggest few hydrophobic amino acid groups, of the order of 10 to 15 at the contact areas of each half-molecule or decamer. 4. The further dissociation of the decamers to dimers and the dimers to monomers indicates the presence of a larger number of amino acid groups of ca 35-40/dimer and 100-120/monomer. 5. This suggests hydrophobic stabilization of the dimer to dimer and monomer to monomer contacts within the decamers, as observed with other molluscan hemocyanins.
摘要
通过光散射发现双壳贝类生物——扁玉螺（Say）的血蓝蛋白分子量为8.0±0.6×10⁶。利用扫描透射电子显微镜（STEM）进行质量测量，得出天然颗粒的粒子质量为8.25±0.42×10⁶，半分子的粒子质量为4.09±0.20×10⁶。2. 血蓝蛋白亚基在pH 8.0的8.0 M尿素和6.0 M盐酸胍中完全解离，在pH 11.0、0.01 M乙二胺四乙酸（EDTA）中解离后的分子量分别为4.38×10⁵、4.22×10⁵和4.71×10⁵，接近扁玉螺血蓝蛋白及大多数腹足纲动物血蓝蛋白母分子量的二十分之一。3. 对在pH 8.0、1×10⁻² M Mg²⁺、1×10⁻² M Ca²⁺以及pH 8.0、3×10⁻³ M Ca²⁺条件下研究的尿素解离转变进行分析，结果表明在每个半分子或十聚体的接触区域，疏水氨基酸基团数量很少，约为10到15个。4. 十聚体进一步解离为二聚体，二聚体再解离为单体，这表明每个二聚体存在约35 - 40个氨基酸基团，每个单体存在100 - 120个氨基酸基团。5. 这表明十聚体内二聚体与二聚体以及单体与单体之间的接触存在疏水稳定性，这与其他软体动物血蓝蛋白的情况一致。
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