Measurement of dipolar couplings in a transducin peptide fragment weakly bound to oriented photo-activated rhodopsin.
Measurement of dipolar couplings in a transducin peptide fragment weakly bound to oriented photo-activated rhodopsin.
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测量与定向光激活视紫红质弱结合的转导蛋白肽片段中的偶极耦合。
DOI：
10.1023/a:1008378523816
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发表时间：
2000
影响因子：
2.7
通讯作者：
Bax,A
中科院分区：
文献类型：
--
作者：
Koenig,BW;Mitchell,DC;Konig,S;Grzesiek,S;Litman,BJ;Bax,A
从牛视网膜杆外节分离的含视紫红质的盘，在高磁场下与其膜垂直平行于磁场对齐。视紫红质光活化后，C-末端转导素11肽的瞬时结合，选择性地在Leu 5和Gly 9处用15 N标记，导致这两个残基对1 JNH分裂的残余偶极贡献。这两个残基显示1 JNH分裂，这是小于在黑暗适应或视紫红质的样品，并返回到其各向同性的值，由视紫红质的Meta II状态的衰减率确定。偶极耦合表明，在束缚态下，Leu 5和Gly 9的N-H矢量分别与圆盘法线成48±4°和40±8°角。 这些“转移”偶极耦合可能提供了一个有用的方法，用于研究灵活的，低亲和力的配体的构象和取向时，绑定到定向的整体膜受体。
Rhodopsin-containing disks, isolated from rod outer segments of bovine retina, align at high magnetic fields with their membrane normal parallel to the magnetic field. After light-activation of rhodopsin, transient binding of the C-terminal transducin undecapeptide, selectively labeled with15N at Leu5and Gly9, results in residual dipolar contributions to the1JNHsplittings for these two residues. Both residues show1JNHsplittings which are smaller than in the dark-adapted or rhodopsin-free sample, and return to their isotropic values at a rate determined by the decay of the meta II state of rhodopsin. The dipolar couplings indicate that in the bound state, N-H vectors of Leu5and Gly9make angles of 48±4° and 40±8°, respectively, with the disk normal. These `transferred' dipolar couplings potentially offer a useful method for studying the conformation and orientation of flexible, low affinity ligands when bound to oriented integral membrane receptors.