5. Tutorials

5.1. Visualize spectra

A tutorial on how to load and display 1D NMR spectra is presented in Getting started.

Here, we load and inspect 2D relaxation spectra of glycine and L-histidine hydrochloride monohydrate with magic angle spinning solid-state NMR spectroscopy. The data folders for glycine and histidine are in the GLY and HISTCM folders. Drag and drop both folders to the Workflow of EasyNMR. Two transient Folder objects are created. Extract experiments 401 and 412 from the GLY and HISTCM folders, respectively, by clicking on the Extract button. These two experiments are marked as Bruker 2D spectrum.

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Loading two 2D relaxation spectra for glycine and L-histidine hydrochloride monohydrate.

Double click on the glycine Plot object. You can see the 15N chemical shift in the horizontal axis and delay time in the T1 measurement method of Torchia (J. Magn. Reson. 30 (3): 613-616) in the vertical axis. The glycine signal at \(\delta_{Gly} = 32.9 \textrm{ ppm}\) disappears in approximately 2 seconds - five times that of the T1 value for this amine site - with an approximate relaxation time of T1, Gly = 0.4 s.

_images/easynmr_tutorial_2d_histgly_plotglycine_time.jpg

Two-dimensional 15N relaxation ordered spectroscopy of glycine with solid-state NMR. The vertical axis is delay time for T1 relaxation measurement, while the horizontal axis is the 15N chemical shift.

Now, double click on the histidine Plot object. There are three nitogen sites in L-histidine hydrochloride monohydrate: \(\delta_{A} = 47 \textrm{ ppm}\) for the amine nitrogen, \(\delta_{\epsilon} = 176 \textrm{ ppm}\) for the nitrogen nuclei farthest from the branch, and \(\delta_{\delta} = 189 \textrm{ ppm}\) for the imidazole nitrogen closest to the branch. With the default magnification, in the 2D \(t_{Delay} - \delta\) plot, you can only see the \(\textrm{N}^{\delta}\) and \(\textrm{N}^{\epsilon}\) peaks.

_images/easynmr_tutorial_2d_histgly_plothistidine_time.jpg

Two-dimensional 15N relaxation ordered spectroscopy of histidine with solid-state NMR. The vertical axis is delay time for T1 relaxation measurement, while the horizontal axis is the 15N chemical shift.

The \(\textrm{N}^{\delta}\) and \(\textrm{N}^{\epsilon}\) sites have long relaxation times. Their signal was not completely relax, even after 8000 seconds! In fact, \(T_{1, \delta} = 3120 \textrm{ s}\) and \(T_{1, \epsilon} = 2720 \textrm{ s}\).

Use the Zoom tool in the Plot toolbar to inspect the amine peak. Magnify the area around the amine region and repeat this process until you see the amine peak.

_images/easynmr_tutorial_2d_histgly_plothistidine_zoomcropped.jpg

Use the Zoom tool to magnify the amine region of the plot.

_images/easynmr_tutorial_2d_histgly_plothistidine_zooming.jpg

Zooming into the amine region.

The amine peak in histidine disappears in approximately 8 seconds with \(T_{1, A} = 1.8 \textrm{ s}\)

_images/easynmr_tutorial_2d_histgly_plothistidine_aminepeak.jpg

Amine regione of histidine data.

You can fit the time domain data to extract \(T_1\) values using a combination of Trace and Model objects.

5.2. Numerical simulations with SIMPSON

SIMPSON tutorials may be accessed from here, where you can choose between nine basic examples, four examples for proteins, and two advanced examples. These tutorials are published in Annu. Rep. NMR 100, 1, 2020 (open access preview).