Natural abundant ~15N NMR detection of polypeptide and protein

摘要

THE ~(15)N NMR study is of general interest in the analysis of the protein conformations in solutions. When NMR is applied to the conformation study of macrobiomolecules; a heteronuclear multiple quantum coherence (HMQC) spectrum of ~(15)N is usuallymeasured first, so that the amide protons are assigned before other experiments, such as the total correlation spectroscopy (TOCSY) and the nuclear Overhauser enhancement spectroscopy (NOESY), are performed. Because of the extremely low natural abundanceof ~(15)N (about 0.37 % ), direct ~15N NMR measurements on proteins are nearly not possible. When a protein is labeled by ~(15)N, its solution structure is more easily to be determined using three-dimensional, or even higher-dimensional NMR experiments.However, many proteins are purified from the natural products. Purification is usually not an easy task. It is much more difficult to get a ~(15)N-enriched sample. In fact, isotope labeling is rather demanding and involves many time-consuming and expensive processes, which could not be afforded by many laboratories. Therefore, natural abundant ~(15)N NMR study is of great importance.