Positive and negative cooperativities at subsequent steps of oxygenation regulate the allosteric behavior of multistate sebacylhemoglobin.
Positive and negative cooperativities at subsequent steps of oxygenation regulate the allosteric behavior of multistate sebacylhemoglobin.
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随后的氧合步骤中的正向和负向协同作用调节多态癸二酰血红蛋白的变构行为。
DOI：
10.1021/bi952446b
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
Gilliland,G
中科院分区：
文献类型：
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作者：
Bucci,E;Razynska,A;Kwansa,H;Gryczynski,Z;Collins,JH;Fronticelli,C;Unger,R;Braxenthaler,M;Moult,J;Ji,X;Gilliland,G
通过与双（3，5-二溴水杨基）癸二酸酯反应获得交联人血红蛋白（HbA）。肽图和晶体学分析证实存在10个碳原子长的癸二酸残基，其交联β-裂缝（DecHb）的两个β82赖氨酸。从氧结合等温线获得的Adair常数表明，在氧合的第一步，正常血红蛋白和DecHb具有非常相似的氧亲和力。在DecHb中，负结合协同性存在于氧合的第二步，其亲和力比第一步低27倍。在第三步结合中存在正协同效应，其亲和力是第二步的380倍。第四结合步骤显示出弱的负协同性，亲和力为第三步骤的一半。脱氧-DecHb晶体衍射至1.9 nm分辨率。得到的原子坐标与Fermi等人[（1984）J.Mol.Biol.175，159 - 174]和Fronticelli等人[（1994）J.Biol.Chem. 269，23965 - 23969]对脱氧HbA的原子坐标非常相似。脱氧-DecHb的电子密度图表明β82赖氨酸之间存在10碳桥。分子建模证实，将接头插入T结构仅需要两个β82赖氨酸的轻微置换。相反，将接头插入R和R2结构[Shaanan（1983）J. Mol. Biol. 171，31 - 59; Silva等人（1992）J.Biol.Chem.267，17248 - 17256]受到严重的空间限制的阻碍。接头主要影响血红蛋白的部分和完全配体状态。这些数据表明，在DecHb协调的构象变化，在每个步骤的氧合。
Cross-linked human hemoglobin (HbA) is obtained by reaction with bis(3,5-dibromosalicyl) sebacate. Peptide maps and crystallographic analyses confirm the presence of the 10 carbon atom long sebacyl residue cross-linking the two β82 lysines of the β-cleft (DecHb). The Adair's constants, obtained from the oxygen binding isotherms, show that at the first step of oxygenation normal hemoglobin and DecHb have a very similar oxygen affinity. In DecHb negative binding cooperativity is present at the second step of oxygenation, which has an affinity 27 times lower than at the first step. Positive cooperativity is present at the third binding step, whose affinity is 380 times that of the second step. The fourth binding step shows a weak negative cooperativity with an affinity one-half that of the third step. Crystals of deoxy-DecHb diffracted to 1.9 Å resolution. The resulting atomic coordinates are very similar to those of Fermi et al. [(1984)J.Mol.Biol.175, 159−174] and Fronticelli et al. [(1994)J.Biol.Chem. 269, 23965−23969] for deoxy-HbA. The electron density map of deoxy-DecHb indicates the presence of the 10 carbon bridge between the β82 lysines. Molecular modeling confirms that insertion of the linker into the T structure requires only slight displacement of the two β82 lysines. Instead, insertion of the linker into the R and R2 structures [Shaanan (1983)J. Mol. Biol.171, 31−59; Silva et al. (1992)J. Biol. Chem.267, 17248−17256] is hindered by serious sterical restrictions. The linker primarily affects the partially and fully liganded states of hemoglobin. The data suggest in DecHb concerted conformational changes at each step of oxygenation.