Baudin V, Dumoulin A, Poyart C, Pagnier J
INSERM U229, Hôpital de Bicêtre, Le Kremlin Bicêtre.
Transfus Clin Biol. 1995;2(6):463-7. doi: 10.1016/s1246-7820(05)80072-2.
The search for human Hb variants exhibiting a low oxygen affinity without requiring 2,3-diphosphoglycerate, together with a low oxygation rate, is of an increased interest in the view of producing an artificial oxygen carrier. We have synthesized the recombinant Hb beta 41Phe-->Tyr (rHb beta F41Y) which exhibits a low oxygen affinity due to the stabilization of the deoxy state of tetrameric Hb [1]. Interestingly, the autooxydation rate for this mutant is similar to that for Hb A. We have associated the mutation beta F41Y with the naturally occurring beta 82Lys-->Asp substitution (Hb Providence) known to be responsible for a low oxygen affinity [2]. The second-site mutation further decreases the oxygen affinity of the rHb beta F41Y. The effects of the beta F41Y and K82D mutations are additive, resulting in a four fold decrease in oxygen affinity of the artificial mutant Hb beta F41Y-K82D, compared to Hb A. In spite of the marked decrease in oxygen affinity, the autooxydation rate is 2- to 3 fold larger than that of Hb A. These data show that it is possible to adjust the oxygen binding properties of human Hb by using protein engineering methods. Because of the low oxygen affinity coexisting with a moderately increased autooxydation rate, this variant is a good candidate for the development of a Hb-based oxygen carrier.
鉴于人工氧载体的研发，寻找那些无需2,3-二磷酸甘油酸且氧合速率较低的低氧亲和力人类血红蛋白（Hb）变体，已引发了越来越多的关注。我们合成了重组血红蛋白β 41Phe→Tyr（rHbβF41Y），由于四聚体血红蛋白脱氧状态的稳定，它表现出低氧亲和力[1]。有趣的是，该突变体的自氧化速率与血红蛋白A相似。我们将βF41Y突变与已知导致低氧亲和力的天然存在的β82Lys→Asp替换（血红蛋白普罗维登斯）相结合[2]。第二位点突变进一步降低了rHbβF41Y的氧亲和力。βF41Y和K82D突变的影响是累加的，与血红蛋白A相比，人工突变体血红蛋白βF41Y-K82D的氧亲和力降低了四倍。尽管氧亲和力显著降低，但其自氧化速率比血红蛋白A高2至3倍。这些数据表明，通过蛋白质工程方法可以调节人类血红蛋白的氧结合特性。由于低氧亲和力与适度增加的自氧化速率并存，该变体是开发基于血红蛋白的氧载体的良好候选者。
