Self-association, cooperativity and supercooperativity of oxygen binding by hemoglobins.
Self-association, cooperativity and supercooperativity of oxygen binding by hemoglobins.
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血红蛋白与氧结合的自缔合性、协同性和超协同性。
DOI：
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发表时间：
1998
影响因子：
2.8
通讯作者：
A. Riggs
中科院分区：
文献类型：
--
作者：
A. Riggs
四聚体脊椎动物血红蛋白（Hbs）的协同配体结合使得在比其他情况下更高的压力下输送氧气成为可能。这种协同性取决于四聚体内二聚体-二聚体相互作用的变化，并反映在pH 7.4下氧合后人Hb中四聚体-二聚体解离常数增加50000倍，从约2x 10（-11）mol l-1增加到约10（-6）mol l-1。血红蛋白在非脊椎动物中广泛存在这种依赖于配体的结合变化，其机制与脊椎动物中的有很大不同。寡聚血红蛋白已被确定在生物体中的五个门（软体动物，棘皮动物，环节动物，phoronids和脊索动物），解离亚基氧化后的血红素铁和重新结合的三价铁配体，如CN-，N3-或NO2-。因此，血红素铁的价态和配体状态控制着临界亚基界面的稳定性。这种现象的广泛分布表明，血红素和界面之间的通信可能是几乎普遍的非脊椎动物血红蛋白之间的共同机制。这种相互作用可能类似于已知的软体动物Scapharca inaequalivis的同二聚体Hb。虽然肌肉组织血红蛋白或肌红蛋白（肌红蛋白）通常是单体的，与非合作O2结合，腹足类软体动物和石鳖的radular肌肉有同型二聚体的肌红蛋白结合O2合作。合作的非肌肉组织血红蛋白也已确定。这些包括纽形虫Cerebratulus lacteus的神经Hb和潜水甲虫Anisops assimilis的Hb，其表现出与高希尔系数相关的单体的脱氧依赖性自缔合。计算表明，2-3 mmol L-1浓度的血红蛋白的血红素的基础上在大脑中的Cerebratulus应大大延长时间作为一个积极的捕食者在缺氧或缺氧的环境。氧从血红蛋白的Anisops被输送到一个气泡，从而控制浮力密度。许多HBS的两栖动物，爬行动物，鸟类和一些胚胎哺乳动物表现出进一步的'supercooperativity'的O2结合，这取决于可逆的脱氧依赖性四聚体-四聚体协会，形成一个集合具有非常低的亲和力O2。这种现象导致O2-结合曲线比单独的四聚体更陡。增加的协同性应导致递送到组织的O2量的增加，并且对鸟类飞行肌肉特别有价值。
Cooperative ligand binding by tetrameric vertebrate hemoglobins (Hbs) makes possible the delivery of oxygen at higher pressures than would otherwise occur. This cooperativity depends on changes in dimer-dimer interactions within the tetramer and is reflected in a 50 000-fold increase in the tetramer-dimer dissociation constant in human Hb upon oxygenation at pH 7.4, from approximately 2x10(-11)mol l-1 to approximately 10(-6)mol l-1. Hbs that undergo such ligand-dependent changes in association are widespread in non-vertebrates, where the mechanisms are very different from those in vertebrates. Oligomeric Hbs have been identified in organisms in five phyla (molluscs, echinoderms, annelids, phoronids and chordates) that dissociate to subunits upon oxidation of the heme iron and reassociate with the binding of ferric iron ligands such as CN-, N3- or NO2-. Thus, the valence and ligand state of the heme iron control the stability of a critical subunit interface. The broad distribution of this phenomenon suggests a common mechanism of communication between heme and interface that may be almost universal among non-vertebrate Hbs. This interaction may be similar to that known for the homodimeric Hb of the mollusc Scapharca inaequivalvis. Although muscle tissue Hbs or myoglobins (Mbs) are usually monomeric, with non-cooperative O2 binding, the radular muscles of gastropod molluscs and chitons have homodimeric Mbs that bind O2 cooperatively. Cooperative non-muscle tissue Hbs have also been identified. These include the neural Hb of the nemertean worm Cerebratulus lacteus and the Hb of the diving beetle Anisops assimilis, which exhibit deoxygenation-dependent self-association of monomers that is associated with high Hill coefficients. Calculations suggest that the 2-3 mmol l-1 concentration of Hb on a heme basis in the brain of Cerebratulus should substantially extend the time as an active predator in an anaerobic or hypoxic environment. Oxygen from the Hb of Anisops is delivered to a gas bubble and thereby controls the buoyant density. Many Hbs of amphibians, reptiles, birds and some embryonic mammals exhibit a further 'supercooperativity' of O2 binding which depends on reversible deoxygenation-dependent tetramer-tetramer association to form an assemblage with a very low affinity for O2. This phenomenon results in steeper O2-binding curves than exhibited by tetramers alone. The increased cooperativity should result in an increase in the amount of O2 delivered to the tissues and should be especially valuable for avian flight muscles.
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影响因子：
2.9
作者：
Doyle,ML;Lew,G;DeYoung,A;Kwiatkowski,L;Wierzba,A;Noble,RW;Ackers,GK
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DOI：
10.1073/pnas.93.25.14526
发表时间：
1996-12
影响因子：
11.1
作者：
William E. Royer;A. Pardanani;Quentin H. Gibson;Quentin H. Gibson;Eric S. Peterson;Joel M. Friedman
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牛蛙（Rana catesbeiana）的血红蛋白。
DOI：
--
发表时间：
1993
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Tam,LT;Manning,D;Cox,DJ;Riggs,AF
通讯作者：
Riggs,AF
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DOI：
10.1021/bi971382x
发表时间：
1997
期刊：
Biochemistry.
影响因子：
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作者：
Ackers,GK;Perrella,M;Holt,JM;Denisov,I;Huang,Y
通讯作者：
Huang,Y
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影响因子：
5.6
作者：
Mitchell,DT;Kitto,GB;Hackert,ML
通讯作者：
Hackert,ML