BINDING OF CARBON DIOXIDE BY HORSE HAEMOGLOBIN
BINDING OF CARBON DIOXIDE BY HORSE HAEMOGLOBIN
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DOI：
10.1042/bj1240031
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发表时间：
1971-01-01
影响因子：
4.1
通讯作者：
ROSSIBER.L
中科院分区：
文献类型：
--
作者：
KILMARTIN, JV;ROSSIBER.L
1.已经制备了三种修饰的马血红蛋白：（i）αc2βc2，其中α-和β-链的α-氨基都与氰酸酯反应，（ii）αc2β2，其中α-链的α-氨基与氰酸酯反应，和（iii）α2βc2，其中β-链的两个α-氨基与氰酸酯反应。2.αc2βc2、α2β c2和αc2β 2的希尔常数n值分别为2.5、2.0和2.6，表明所有衍生物的血红素基团之间存在协同相互作用。3.在碱性pH范围内（约pH8.0），所有衍生物的电荷都与正常血红蛋白相同，而在酸性pH范围内（约pH6.0），αc2β c2与正常血红蛋白相差4个质子电荷，αc2β2，α2β c2与正常血红蛋白相差2个质子电荷，表明预期数量的电离基团已被去除。4.αc2β 2和αc2β c2的碱性玻尔效应降低了25%，而α2βc2的碱性玻尔效应与正常血红蛋白相同。5.脱氧型αc2β c2与CO2的结合并不比氧型αc2βc2多，而αc2β 2和α2β c2则表现出中等结合。6.实验结果证实了在生理条件下血红蛋白通过末端4个α-氨基与CO2结合的假设，以及α-链末端2个α-氨基参与玻尔效应的假设。
1. Three modified horse haemoglobins have been prepared: (i) αc2βc2, in which both the α-amino groups of the α- and β-chains have reacted with cyanate, (ii) αc2β2, in which the α-amino groups of the α-chains have reacted with cyanate, and (iii) α2βc2, in which the two α-amino groups of the β-chain have reacted with cyanate. 2. The values ofn(the Hill constant) for αc2βc2, α2βc2and αc2β2were (respectively) 2.5, 2.0 and 2.6, indicating the presence of co-operative interactions between the haem groups for all derivatives. 3. In the alkaline pH range (about pH8.0) all the derivatives show the same charge as normal haemoglobin whereas in the acid pH range (about pH6.0) αc2βc2differs by four protonic charges and αc2β2, α2βc2by two protonic charges from normal haemoglobin, indicating that the expected number of ionizing groups have been removed. 4. αc2β2and αc2βc2show a 25% decrease in the alkaline Bohr effect, in contrast with α2βc2, which has the same Bohr effect as normal haemoglobin. 5. The deoxy form of αc2βc2does not bind more CO2than the oxy form of αc2βc2, whereas αc2β2and α2βc2show intermediate binding. 6. The results reported confirm the hypothesis that, under physiological conditions, haemoglobin binds CO2through the four terminal α-amino groups and that the two terminal α-amino groups of α-chains are involved in the Bohr effect.