| Autor: |
A, Dumoulin, L, Kiger, N, Griffon, C, Vasseur, I, Kister, P, Génin, M C, Marden, J, Pagnier, C, Poyart |
| Rok vydání: |
1996 |
| Předmět: |
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| Zdroj: |
Protein science : a publication of the Protein Society. 5(1) |
| ISSN: |
0961-8368 |
| Popis: |
Based on the properties of two low oxygen affinity mutated hemoglobins (Hb), we have engineered a double mutant Hb (rHb beta YD) in which the beta F41Y substitution is associated with K82D. Functional studies have shown that the Hb alpha 2 beta 2(C7)F41Y exhibits a decreased oxygen affinity relative to Hb A, without a significantly increased autooxidation rate. The oxygen affinity of the natural mutant beta K82D (Hb Providence-Asp) is decreased due to the replacement of two positive charges by two negative ones at the main DPG-binding site. The functional properties of both single mutants are interesting in the view of obtaining an Hb-based blood substitute, which requires: (1) cooperative oxygen binding with an overall affinity near 30 mm Hg at half saturation, at 37 degrees C, and in the absence of 2,3 diphosphoglycerate (DPG), and (2) a slow rate of autooxidation in order to limit metHb formation. It was expected that the two mutations were at a sufficient distance (20 A) that their respective effects could combine to form low oxygen affinity tetramers. The double mutant does display additive effects resulting in a fourfold decrease in oxygen affinity; it can insure, in the absence of DPG, an oxygen delivery to the tissues similar to that of a red cell suspension in vivo at 37 degrees C. Nevertheless, the rate of autooxidation, 3.5-fold larger than that of Hb A, remains a problem. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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