Ishima Rieko, Torchia Dennis A
Molecular Structural Biology Unit, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892-4307, USA.
J Biomol NMR. 2003 Mar;25(3):243-8. doi: 10.1023/a:1022851228405.
Relaxation compensated constant-time Carr-Purcell-Meiboom-Gill relaxation dispersion experiments for amide protons are presented that detect mus-ms time-scale dynamics of protein backbone amide sites. Because of their ten-fold larger magnetogyric ratio, much shorter 180 degrees pulses can be applied to (1)H than to (15)N spins; therefore, off-resonance effects are reduced and a wider range of effective rf fields can often be used in the case of (1)H experiments. Applications to [(1)H-(15)N]-ubiquitin and [(1)H-(15)N]-perdeuterated HIV-1 protease are discussed. In the case of ubiquitin, we present a pulse sequence that reduces artifacts that arise from homonuclear (3)J(H(N)-H(alpha)) coupling. In the case of the protease, we show that relaxation dispersion of both (1)H and (15)N spins provides a more comprehensive picture of slow backbone dynamics than does the relaxation dispersion of either spin alone. We also compare the relative merits of (1)H versus (15)N transverse relaxation measurements and note the benefits of using a perdeuterated protein to measure the relaxation dispersion of both spin types.
本文介绍了用于酰胺质子的弛豫补偿恒时 Carr-Purcell-Meiboom-Gill 弛豫色散实验，该实验可检测蛋白质主链酰胺位点的微秒至毫秒时间尺度动力学。由于氢核的旋磁比大十倍，因此与氮-15 自旋相比，氢-1 可施加更短的 180°脉冲；所以，在氢-1 实验中，失谐效应会降低，并且通常可以使用更宽范围的有效射频场。文中讨论了该实验在[氢-1-氮-15]泛素和[氢-1-氮-15]全氘代 HIV-1 蛋白酶中的应用。对于泛素，我们提出了一种脉冲序列，可减少由同核 J(H(N)-H(α))耦合产生的伪影。对于蛋白酶，我们表明氢-1 和氮-15 自旋的弛豫色散比单独任何一种自旋的弛豫色散能提供更全面的慢主链动力学信息。我们还比较了氢-1 与氮-15 横向弛豫测量的相对优点，并指出使用全氘代蛋白质来测量两种自旋类型弛豫色散的好处。
