本研究通过使用灵敏度增强的带梯度形状脉冲进行异核单量子相干(HSQC)实验检测保健食品中违法添加的西地那非类物质。待测样品以甲醇溶解超声辅助提取,减压浓缩后以氘代DMSO溶解上机测试;利用Assure-NMR软件将得到的未知样品异核单量子...本研究通过使用灵敏度增强的带梯度形状脉冲进行异核单量子相干(HSQC)实验检测保健食品中违法添加的西地那非类物质。待测样品以甲醇溶解超声辅助提取,减压浓缩后以氘代DMSO溶解上机测试;利用Assure-NMR软件将得到的未知样品异核单量子相干(Heteronculear Single Quantum Coherence)谱图与已知西地那非类物质谱图进行模拟匹配。本方法检出限可以达到200μg·kg-1,能快速有效的对保健食品中西地那非类物质的违法添加侦察识别。该方法简便快捷,可以为食品安全监管部门提供一种新颖便捷的那非类物质监管稽查参考办法。展开更多
Phase sensitive HMQC(Heteronuclear Multiple Quantum Coherence) and HSQC(Heteronuclear Single Quantum Coherence) experiments with t 1 noise reduction are proposed for the accurate measurement of heteronuclear one bond ...Phase sensitive HMQC(Heteronuclear Multiple Quantum Coherence) and HSQC(Heteronuclear Single Quantum Coherence) experiments with t 1 noise reduction are proposed for the accurate measurement of heteronuclear one bond 13 C 1H coupling constants. The resulting 2D spectra give anti phase splittings of heteronuclear one bond couplings along ω 2 dimension, so that the precision of coupling constant measurement is less subject to the residual t 1 noise. By combining use of data fitting procedure on a spectrum with enough digital resolution and signal to noise ratio, a precision of about 0 03 Hz can be achieved in the measurement of heteronuclear one bond coupling constants. The proposed method can be very useful for the study of residual dipolar couplings caused by the alignment in high magnetic field and the dynamic frequency shift caused by the cross correlation between chemical shift and spin dipolar interactions.展开更多
人源转录调控因子MRG15(MORF4related gene on chromosome 15)是在胚胎发育,细胞增殖和衰老过程中具有重要作用的蛋白质.在分子水平上,MRG15的chromo结构域能够与组蛋白H3甲基化的肽段H3K36me3相互作用.为了确定二者的作用位点和方式,...人源转录调控因子MRG15(MORF4related gene on chromosome 15)是在胚胎发育,细胞增殖和衰老过程中具有重要作用的蛋白质.在分子水平上,MRG15的chromo结构域能够与组蛋白H3甲基化的肽段H3K36me3相互作用.为了确定二者的作用位点和方式,利用液体核磁共振的方法对MRG15 chromo结构域和H3K36me3多肽进行了研究.对MRG15chromo结构域进行归属,用化学位移扰动的方法研究了其与H3K36me3肽段的相互作用,确定了相互作用位点的关键氨基酸为H21,Y46,W49和W53,并计算了解离常数约为1mmol/L.研究结果对于阐明MRG15与组蛋白H3的结合和相互作用机制提供了重要的线索.展开更多
文摘本研究通过使用灵敏度增强的带梯度形状脉冲进行异核单量子相干(HSQC)实验检测保健食品中违法添加的西地那非类物质。待测样品以甲醇溶解超声辅助提取,减压浓缩后以氘代DMSO溶解上机测试;利用Assure-NMR软件将得到的未知样品异核单量子相干(Heteronculear Single Quantum Coherence)谱图与已知西地那非类物质谱图进行模拟匹配。本方法检出限可以达到200μg·kg-1,能快速有效的对保健食品中西地那非类物质的违法添加侦察识别。该方法简便快捷,可以为食品安全监管部门提供一种新颖便捷的那非类物质监管稽查参考办法。
文摘Phase sensitive HMQC(Heteronuclear Multiple Quantum Coherence) and HSQC(Heteronuclear Single Quantum Coherence) experiments with t 1 noise reduction are proposed for the accurate measurement of heteronuclear one bond 13 C 1H coupling constants. The resulting 2D spectra give anti phase splittings of heteronuclear one bond couplings along ω 2 dimension, so that the precision of coupling constant measurement is less subject to the residual t 1 noise. By combining use of data fitting procedure on a spectrum with enough digital resolution and signal to noise ratio, a precision of about 0 03 Hz can be achieved in the measurement of heteronuclear one bond coupling constants. The proposed method can be very useful for the study of residual dipolar couplings caused by the alignment in high magnetic field and the dynamic frequency shift caused by the cross correlation between chemical shift and spin dipolar interactions.
