High frequency (139.5 GHz) electron paramagnetic resonance spectroscopy of the GTP form of p21 ras with selective 17O labeling of threonine.
High frequency (139.5 GHz) electron paramagnetic resonance spectroscopy of the GTP form of p21 ras with selective 17O labeling of threonine.
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p21 ras GTP 形式的高频 (139.5 GHz) 电子顺磁共振波谱，选择性 17O 标记苏氨酸。
DOI：
10.1021/bi9605954
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
Singel,DJ
中科院分区：
文献类型：
--
作者：
Halkides,CJ;Bellew,BF;Gerfen,GJ;Farrar,CT;Carter,PH;Ruo,B;Evans,DA;Griffin,RG;Singel,DJ
本文用139.5GHz电子顺磁共振谱研究了Mn（Ⅱ）与鸟苷（GTP）类似物5 ′-（β，γ-亚氨三磷酸）的配合物p21 ras。研究的p21样品用[17 O γ]苏氨酸选择性标记至最终富集30%。Mn（II）− 17 O的超精细相互作用被观察到，但耦合常数的值为0.11 ± 0.04 mT，是迄今为止报道的最小值。从头计算表明，该值与苏氨酸羟基的直接配位一致，并提供了Mn（II）− 17 O键长的估计值为2.7 π。测得的超精细耦合常数和相关的键长与Mn（II）− 17 O配位络合物的典型值形成鲜明对比，分别为<$0.25 mT和<$2.2 mT。这种对比强调了p21中Mn（II）−O相互作用的特殊弱点，并令人信服地认为，核苷酸诱导的构象变化（已知包括p21中涉及Thr 35的区域）不是由Mn（II）与Thr 35羟基的配位驱动的。
Electron paramagnetic resonance spectroscopy at 139.5 GHz has been used to study p21rascomplexed with Mn(II) and guanosine 5‘-(β,γ-imidotriphosphate), an analog of GTP. The p21 sample studied was selectively labeled with [17Oγ]threonine to a final enrichment of 30%. A Mn(II)−17O hyperfine interaction was observed, but the value of the coupling constant, 0.11 ± 0.04 mT, is the smallest such value yet reported.Ab initiocalculations indicate that this value is consistent with direct coordination of the threonine hydroxyl group and provide an estimate for the Mn(II)−17O bond length of 2.7 Å. The measured hyperfine coupling constant and associated bond length starkly contrast with typical values for Mn(II)−17O coordination complexes, namely, ∼0.25 mT and ∼2.2 Å, respectively. This contrast underscores the peculiar weakness of this Mn(II)−O interaction in p21 and persuasively argues that the nucleotide-induced conformational change, which is known to encompass the region of p21 involving Thr35, is not driven by Mn(II) coordination of the Thr35 hydroxyl group.