Alam T M, Orban J, Drobny G P
Department of Chemistry, University of Washington, Seattle 98195.
Biochemistry. 1991 Sep 24;30(38):9229-37. doi: 10.1021/bi00102a014.
Backbone dynamics in the [5',5"-2H2]2'-deoxythymidine labeled duplex dodecamer [d-(CGCGAATTCGC)]2 have been investigated by solid-state 2H NMR. Quadrupolar echo line shapes, spin-lattice relaxation, and quadrupolar echo decay times were obtained over hydration levels ranging from W = 0.0 to 25.2 (moles of H2O/mole of nucleotide). Variation of the line shape with changing hydration level was analyzed by using models employed in previous investigations of dodecamer base and sugar dynamics. Both fast local motions and a slower helix motion were present within the oligonucleotide. The fast motion was modeled as a four-site libration whose amplitude increased with hydration level. The root mean square amplitude of this librational model was 2-6 degrees larger than the amplitude observed in either the furanose ring or base labeled material for the entire range of hydration levels investigated. The observed line shape was inconsistent with a rapid three-site trans-gauche isomerization. A slow motion about the helix axis was observed at low water levels and increased in rate and amplitude with hydration. This motional model is in agreement with previous oligonucleotide studies.
通过固态2H NMR研究了[5',5"-2H2]2'-脱氧胸苷标记的双链十二聚体[d-(CGCGAATTCGC)]2中的主链动力学。在水合水平范围从W = 0.0至25.2（水的摩尔数/核苷酸的摩尔数）内获得了四极回波线形、自旋晶格弛豫和四极回波衰减时间。通过使用先前对十二聚体碱基和糖动力学研究中采用的模型，分析了线形随水合水平变化的情况。在寡核苷酸内同时存在快速的局部运动和较慢的螺旋运动。快速运动被模拟为一种四点摆动，其幅度随水合水平增加。在整个研究的水合水平范围内，这种摆动模型的均方根幅度比在呋喃糖环或碱基标记材料中观察到的幅度大2 - 6度。观察到的线形与快速的三点反式-顺式异构化不一致。在低水含量时观察到围绕螺旋轴的缓慢运动，其速率和幅度随水合作用增加。这种运动模型与先前的寡核苷酸研究一致。
