Pellegrini M, Giardina B, Olianas A, Sanna M T, Deiana A M, Salvadori S, Di Prisco G, Tamburrini M, Corda M
Istituto di Chimica Biologica, Università di Cagliari, Italy.
Eur J Biochem. 1995 Dec 1;234(2):431-6. doi: 10.1111/j.1432-1033.1995.431_b.x.
Concerning the number and type of the hemoglobin components, the moray Muraena helena is characterized by three different phenotypes whose frequencies are nearly identical. Thus, the cathodal component is present in all individuals, whereas one or both of two anodal components may be present in the same phenotype. These components have been separated by chromatography. The oxygen binding properties of the purified hemoglobin components have been studied in the absence and presence of saturating concentrations of ATP or GTP and as a function of pH. The cathodal component shows an intrinsic O2 affinity four times higher than that of both anodal components, a very small Bohr effect and a significant decrease in O2 affinity upon addition of ATP and GTP (three and four times respectively with respect to stripped conditions), the latter being more effective than the former over the entire pH range examined. The anodal components do not appear functionally distinguishable and show the presence of an enhanced Bohr effect (Root effect) that is under the strict control of nucleotide triphosphates ATP, GTP, which, unlike in the cathodic component, exert the same effect on oxygen affinity. The complete sequence of the beta chains of the cathodal and of one of the anodal components have been determined. The possible molecular basis of these different functional characteristics are discussed in the light of the globin sequence and of those amino acid residues which are known to be responsible of hemoglobin functional behaviour.
关于血红蛋白成分的数量和类型，海鳝（Muraena helena）具有三种不同的表型，其频率几乎相同。因此，阴极成分存在于所有个体中，而两种阳极成分中的一种或两种可能存在于同一表型中。这些成分已通过色谱法分离。已在不存在和存在饱和浓度的ATP或GTP的情况下以及作为pH的函数研究了纯化的血红蛋白成分的氧结合特性。阴极成分显示出的内在氧亲和力比两种阳极成分高四倍，玻尔效应非常小，并且在添加ATP和GTP后氧亲和力显著降低（相对于脱辅基条件分别降低三倍和四倍），在整个研究的pH范围内，后者比前者更有效。阳极成分在功能上似乎没有区别，并显示出增强的玻尔效应（鲁特效应）的存在，该效应受三磷酸核苷酸ATP、GTP的严格控制，与阴极成分不同，它们对氧亲和力具有相同的影响。已确定了阴极和一种阳极成分的β链的完整序列。根据球蛋白序列以及已知负责血红蛋白功能行为的那些氨基酸残基，讨论了这些不同功能特征的可能分子基础。
