HEMOGLOBIN ALLOSTERY - RESONANCE RAMAN-SPECTROSCOPY OF KINETIC INTERMEDIATES
HEMOGLOBIN ALLOSTERY - RESONANCE RAMAN-SPECTROSCOPY OF KINETIC INTERMEDIATES
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DOI：
10.1126/science.7569921
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发表时间：
1995-09-29
期刊：
影响因子：
56.9
通讯作者：
SPIRO, TG
中科院分区：
文献类型：
--
作者：
JAYARAMAN, V;RODGERS, KR;SPIRO, TG
血红蛋白（Hb）中变构转变的终态R和T在结构上得到了很好的表征，但关于沿着变构途径的中间结构的信息很少。这些中间体进行了检查，通过时间分辨共振拉曼光谱在纳秒到微秒的间隔后，HbCO光解。血红素组和酪氨酸和色氨酸残基的互补光谱记录在436和230纳米的激光激发。这些光谱揭示了一系列交错的第三和第四运动在光周期，涉及近端和远端螺旋的运动，和α（1）β（2）亚基接口。这个序列导致T状态的修改形式，其中α（1）β（2）界面由于两个一氧化碳分子结合到四聚体内的相同二聚体而变形。
The end states, R and T, of the allosteric transition in hemoglobin (Hb) are structurally well characterized, but there is little information on intermediate structures along the allosteric pathway. These intermediates were examined by means of time-resolved resonance Raman spectroscopy in the nanosecond-to-microsecond interval after HbCO photolysis. Complementary spectra of the heme group and of the tyrosine and tryptophan residues were recorded during laser excitation at 436 and 230 nanometers. These spectra reveal a sequence of interleaved tertiary and quaternary motions during the photocycle, motions involving the proximal and distal helices, and the alpha(1) beta(2) subunit interface. This sequence leads to a modified form of the T state, in which the alpha(1) beta(2) interface is deformed as a result of two carbon monoxide molecules binding to the same dimer within the tetramer.