Danell Allison S, Parks Joel H
Rowland Institute at Harvard, Cambridige, Massachusetts 02142, USA.
J Am Soc Mass Spectrom. 2003 Dec;14(12):1330-9. doi: 10.1016/S1044-0305(03)00578-6.
Sensitive methods recently developed to measure laser-induced fluorescence from trapped ions have been applied to study the dynamics of double- and single-stranded oligonucleotides. In this paper, the fraying of duplex terminal base pairs has been identified by measuring the donor fluorescence as a function of temperature from an oligonucleotide duplex labeled with a pair of FRET dyes. Comparison of the degree of dissociation of 14-mer duplexes observed in the mass spectra with the fluorescence intensity of the donor enables intermediate conformations of the unzipping duplex at the weaker binding end of the duplex to be identified. The autodetachment of electrons from double- and single-stranded oligonucleotide anions has been observed in a gas phase environment. To characterize this process, measurements were performed on 7-mers prepared without FRET fluorophores attached. The dependence of the decay rates of trapped anions have been measured as a function of charge state and temperature for various base compositions. An exceptionally strong dependence of the decay rate on base composition has been identified. The physical basis for this process will be discussed.
最近开发的用于测量捕获离子的激光诱导荧光的灵敏方法已被应用于研究双链和单链寡核苷酸的动力学。在本文中，通过测量来自用一对荧光共振能量转移（FRET）染料标记的寡核苷酸双链体的供体荧光随温度的变化，确定了双链末端碱基对的解链情况。将质谱中观察到的14聚体双链体的解离程度与供体的荧光强度进行比较，能够识别双链体较弱结合端解链双链体的中间构象。在气相环境中观察到了双链和单链寡核苷酸阴离子的自电子脱离。为了表征这一过程，对未连接FRET荧光团制备的7聚体进行了测量。测量了捕获阴离子的衰减率随电荷状态和温度的变化，涉及各种碱基组成。已确定衰减率对碱基组成有异常强烈的依赖性。将讨论这一过程的物理基础。
