Allosteric modulation by tertiary structure in mammalian hemoglobins - Introduction of the functional characteristics of bovine hemoglobin into human hemoglobin by five amino acid substitutions
Allosteric modulation by tertiary structure in mammalian hemoglobins - Introduction of the functional characteristics of bovine hemoglobin into human hemoglobin by five amino acid substitutions
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DOI：
10.1074/jbc.270.51.30588
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发表时间：
1995-12-22
影响因子：
4.8
通讯作者：
Brinigar, WS
中科院分区：
文献类型：
--
作者：
Fronticelli, C;Sanna, MT;Brinigar, WS
牛红细胞不含人血红蛋白的主要变构效应物2，3-二磷酸甘油酸。牛血红蛋白具有比人血红蛋白更低的氧亲和力，并且受氯化物的生理浓度调节（Fronticelli，C.，Bucci，E.，和Razynska，A.等人（1988）J. Mol. 202，343-348）。已经提出，牛血红蛋白中的氯调节是通过位于β亚基的A螺旋的氨基末端区域和E螺旋中的特定氨基酸残基引入的（Fronticelli，C.（1990）Biophys. 37，141-146）。根据这一建议，我们构建了两种突变的人血红蛋白，β（V1 M + H2缺失+T4 I + P5 A）和β（V1 M + H2缺失+T4 I + P5 A + A76 K）。这些残基存在于牛血红蛋白中的拟定位置，但位置4处的异亮氨酸除外。氧结合研究表明，这些突变已引入人血红蛋白的低氧亲和力和氯化物敏感性的牛血红蛋白，并揭示了一个以前未被认识到的氧亲和力调节变构机制的存在，其中所有的相互作用，负责降低亲和力和氯离子结合似乎被限制在个别β亚基。
Bovine erythrocytes do not contain 2,3-diphosphoglycerate, the principal allosteric effector of human hemoglobin. Bovine hemoglobin has a lower oxygen affinity than human hemoglobin and is regulated by physiological concentrations of chloride (Fronticelli, C., Bucci, E., and Razynska, A. (1988) J. Mol. Biol. 202, 343-348). It has been proposed that the chloride regulation in bovine hemoglobin is introduced by particular amino acid residues located in the amino-terminal region of the A helix and in the E helix of the beta subunits (Fronticelli, C. (1990) Biophys. Chem. 37, 141-146). In accordance with this proposal we have constructed two mutant human hemoglobins, beta(V1M+H2deleted+T4I+P5A) and beta(V1M+H2deleted+T4I+P5A+A76K). These are the residues present at the proposed locations in bovine hemoglobin except for isoleucine at position 4. Oxygen binding studies demonstrate that these mutations have introduced into human hemoglobin the low oxygen affinity and chloride sensitivity of bovine hemoglobin and reveal the presence of a previously unrecognized allosteric mechanism of oxygen affinity regulation where all the interactions responsible for the lowered affinity and chloride binding appear to be confined to individual beta subunits.