【作者】 涂光忠； 安东各； 马立斌；

【Author】 Tu Guangzhong An Dongge Ma Libin Beijing Institute of Microchemistry,Beijing 100091

【机构】 北京微量化学研究所；

【摘要】 <正>核磁共振的灵敏度较红外光谱和质谱的灵敏度低,所以科学家们采用各种方法来提高核磁共振的灵敏度。增加灵敏度的方法主要有：增强静磁场强度(如90QMHz 谱仪)：超低温探头(CryoProbe)技术：减少溶剂的体积而相应增加样品浓度(如微量样品管和微量探头)；选择最有效的核用于激发和检测(如反式探头)；使用灵敏度增强的梯度场脉冲序列和有效的处理方法等。超低温探头(CryoProbe)技术是一种最有效的提高灵敏度的方法。它的原理是利用极低的温度(约25K)来冷却探头和前置放大器,从而减少 NMR 谱仪中核磁共振信号通道内的电子组件的热噪声,使 NMR 信号的信噪比显著增加。在相同的场强下,超低温探头的灵敏度是常规探头的3～4倍。更多还原

【Abstract】 When the rf coils of an NMR probe are cooled to cryogenic temperatures （ca.25K）,rf efficiency is improved and thermal noise generated by coils is greatly reduced.A further reduction in noise figure is achieved by cooling the rf preamplifier, located within the probe,as well.At the same time the sample temperature is maintained near ambient and regulated by the temperature controller in the usual manner.The overall effect is an improvement in sensitivity of typical 300%.¹⁵N-¹H HSQC spectra were obtained with 4 mM natural abundance protein and 0.05 mM uniformly ¹⁵N-labeled protein using a 500 MHz triple resonance ¹H {¹³C/¹⁵N} NMR CryoProbe with Z-gradient.The experiments time were 2 h 40 min with 32 transient for each t₁ increment.更多还原