Beaven G H, Gratzer W B
Acta Haematol. 1978;60(6):321-8. doi: 10.1159/000207731.
Haemin and protoporphyrin IX, but not bilirubin, are extensively bound by human spectrin. The absorption spectrum of the bound haemin is indicative of coordination of the iron by nitrogenous ligands in the protein. The protoporphyrin IX generates difference spectra on binding, which change with ligand:protein ratio, showing the existence of at least two structurally distinct types of site. The binding of both ligands is complex, and may be cooperative. Binding isotherms, based on spectrophotometric titrations, are given. Haemin and protoporphyrin IX also bind strongly to erythrocyte ghosts. At ionic strengths near physiological we can find no evidence of binding of haemoglobin to spectrin, as judged by sedimentation velocity, and it appears that reported interactions of this nature represent only non-specific binding at low ionic strength.
血红素和原卟啉IX能与人类血影蛋白广泛结合，但胆红素则不能。结合态血红素的吸收光谱表明蛋白质中的含氮配体与铁发生了配位作用。原卟啉IX在结合时会产生差异光谱，该光谱会随配体与蛋白质的比例而变化，这表明至少存在两种结构不同的位点类型。两种配体的结合都很复杂，且可能具有协同性。给出了基于分光光度滴定法的结合等温线。血红素和原卟啉IX也能与红细胞血影紧密结合。在接近生理状态的离子强度下，通过沉降速度判断，我们没有发现血红蛋白与血影蛋白结合的证据，似乎这种性质的报道相互作用仅代表在低离子强度下的非特异性结合。
