Gebauer W, Harris J R, Geisthardt G, Markl J
Institute of Zoology, University of Mainz, Mainz, D-55099, Germany.
J Struct Biol. 1999 Dec 30;128(3):280-6. doi: 10.1006/jsbi.1999.4198.
Keyhole limpet hemocyanin (KLH) is a mixture of two hemocyanin isoforms, termed KLH1 and KLH2. Within KLH1 eight oxygen-binding functional units (FUs), 1-a to 1-h, have been identified, in contrast to KLH2, which was previously thought to be organized in seven FUs (2-a to 2-g). By limited proteolysis of KLH2 subunits, isolation of the polypeptide fragments, and N-terminal sequencing, we have now identified an eighth FU of type h, with a molecular mass of 43 kDa. This is unusually small for a FU h from a gastropodan hemocyanin. It is also shown that KLH2 didecamers can be split into a stable and homogeneous population of decamers by dialysis against 50 mM Tris/HCl, pH 7.5, in the absence of divalent cations. Electron microscopic immunolocalization using a specific monoclonal antibody reveals that FU KLH2-h is located at the collar of the decamer.
钥孔戚血蓝蛋白（KLH）是两种血蓝蛋白同工型的混合物，分别称为KLH1和KLH2。在KLH1中，已鉴定出八个氧结合功能单位（FU），即1-a至1-h，而KLH2之前被认为由七个FU（2-a至2-g）组成。通过对KLH2亚基进行有限的蛋白酶解、分离多肽片段并进行N端测序，我们现在鉴定出了第八个h型FU，其分子量为43 kDa。对于腹足类动物血蓝蛋白的h型FU来说，这个分子量异常小。研究还表明，在不存在二价阳离子的情况下，通过用50 mM Tris/HCl（pH 7.5）进行透析，KLH2十二聚体可以分裂成稳定且均一的十聚体群体。使用特异性单克隆抗体进行的电子显微镜免疫定位显示，FU KLH2-h位于十聚体的颈部。
