Experimental Aspects of Nitrogen-14 NMR Spectroscopy: Application for Study of Biological Molecules

Abstract

Despite the high natural abundance (nearly 100%) and high abundance of Nitrogen-14 isotope in biological systems, applications of ¹⁴N NMR to biological molecules havn’t been radically extended and transformed over the past few years. This is due to low gyromagnetic ratio and strong quadrupolar interaction. The corresponding resonance signals have low resonance frequency and widths ranging from few Hz to several kHz. At low frequencies when weak ¹⁴N FIDs of short duration are recorded, spectra are prone to baseline distortions from the effects of trailing edge of the pulse and acoustic ringing of the probe. All mentioned above factors result in relatively poor S/N, necessitating the use of extensive signal averaging in some cases requiring very long times to obtain a good ¹⁴N spectrum. For all that ¹⁴N NMR today is an essential technique in biochemical research.