HEME-CO AS A PROBE OF THE CONFORMATIONAL STATE OF CALMODULIN
HEME-CO AS A PROBE OF THE CONFORMATIONAL STATE OF CALMODULIN
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DOI：
10.1016/0014-5793(90)81081-x
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发表时间：
1990-10-29
期刊：
影响因子：
3.5
通讯作者：
POYART, C
中科院分区：
文献类型：
--
作者：
MARDEN, MC;LECLERC, L;POYART, C
血红素-CO与钙调蛋白的相互作用，在钙的存在下，导致每个蛋白质四个血红素-CO分子的复合物。在不存在钙的情况下未观察到相互作用。血红素-CO与钙调素的结合通过Soret吸收带从407 nm至420 nm（结合形式）的位移来监测;四个位点在光谱上不相同。配体CO可以从钙调素-血红素-CO复合物中光解，双分子复合动力学也表明是一种非均匀混合物。该复合物不可逆地结合氧。由于钙调素只有一个组氨酸，血红素显然不像血红蛋白那样与铁原子结合，但可能松散地结合在疏水口袋中（Kd=0.5 μM），当蛋白质被钙激活时，这些口袋显然打开。
The interaction of heme-CO with calmodulin, in the presence of calcium, leads to a complex of four heme-CO molecules per protein. No interaction was observed in the absence of calcium. The binding of heme-CO to calmodulin was monitored by the shift in the Soret absorption band from 407 to 420 nm (bound form); the four sites are not spectrally identical. The ligand CO can be photodissociated from the calmodulin-heme-CO complex and the bimolecular recombination kinetics also indicate a heterogeneous mixture. The complex does not bind oxygen reversibly. As calmodulin has only one histidine, the hemes are apparently not bound by the iron atom as in hemoglobin, but are probably loosely associated (Kd=0.5 μM) in hydrophobic pockets which apparently open when the protein is activated by calcium.