Colson-Guastalla H, Aymard C, Chambon J P, Michel F
Biochimie. 1975;57(9):1035-44. doi: 10.1016/s0300-9084(75)80359-2.
The peroxidatic activity of hemoglobin (Hb) is known to be enhanced when this hemoprotein is bound to haptoglobin (Hp). The peroxidatic reaction (H2O2, guaiacol as donor) has been kinetically studied (Steady-state) in the presence of free or rabbit-haptoglobin bound human hemoglobin and some of its derivatives, all in ferricyano-form. With free Hb+ CN, we observed linearity of Lineweaver and Burk plots in a wide range of concentrations, the donor's behaviour was therefore assumed to obey the Michaelis-Menten mechanism. When Hp-Hb+ CN is the enzyme, the donor's behaviour is more complicated, analysis shows the existence of two kinds of donor's binding sites. The possibility whether this behaviour might correspond to the intrinsic properties of Hb chains, as revealed after combination with Hp, was examined. The peroxidatic activity of free and Hp-bound alpha and beta chains of Hb were studied. The alpha chains of Hb combine with Hp whereas the beta chains fail to do so. In order to make useful comparisons, the peroxidatic activity of Hp-bound alpha and beta chains were studied by the use of Hp-semihemoglobin complexes where the semihemoglobins carried heme on only one type of chain (alpha or beta). Results did not show an evident correlation between the activities of the two free or bound types of chains and those of the two classes of binding sites revealed in Hp-Hb+ CN. Moreover, it appeared that the heme-free complementary chain might influence the activity of the heme-carrying alpha or beta chain in semihemoglobins and Hp-semihemoglobin complexes. The binding or protoporphyrin on free and Hp-bound semihemoglobins leads to species which exhibit structures close to that of Hb and Hp-Hb complex respectivley. Results of studies on these derivatives brought up new interesting data : when the porphyrin ring alone is bound to the heme deficient chains (alpha or beta), in Hp-semihemoglobin complexes, the same peculiar behaviour, already observed with Hp-Hb complex, is found again. The structural implications of these results are discussed.
已知当血红蛋白（Hb）与触珠蛋白（Hp）结合时，其过氧化物酶活性会增强。在游离的或与兔触珠蛋白结合的人血红蛋白及其某些衍生物（均为铁氰化物形式）存在的情况下，对过氧化物酶反应（以过氧化氢、愈创木酚为供体）进行了稳态动力学研究。对于游离的Hb + CN，我们在很宽的浓度范围内观察到Lineweaver和Burk图呈线性，因此假定供体的行为符合米氏机制。当Hp - Hb + CN作为酶时，供体的行为更为复杂，分析表明存在两种供体结合位点。研究了与Hp结合后Hb链的内在特性是否可能导致这种行为。研究了游离的和与Hp结合的Hbα链和β链的过氧化物酶活性。Hb的α链能与Hp结合，而β链则不能。为了进行有效的比较，通过使用半血红蛋白复合物（其中半血红蛋白仅在一种类型的链上携带血红素，即α链或β链）研究了与Hp结合的α链和β链的过氧化物酶活性。结果并未显示两种游离或结合类型的链的活性与Hp - Hb + CN中揭示的两类结合位点的活性之间存在明显的相关性。此外，似乎无血红素的互补链可能会影响半血红蛋白和Hp - 半血红蛋白复合物中携带血红素的α链或β链的活性。游离的和与Hp结合的半血红蛋白上结合原卟啉会分别产生结构与Hb和Hp - Hb复合物相近的物种。对这些衍生物的研究结果带来了新的有趣数据：当仅卟啉环与Hp - 半血红蛋白复合物中缺乏血红素的链（α链或β链）结合时，再次发现了与Hp - Hb复合物中已观察到的相同的特殊行为。讨论了这些结果的结构意义。
