Spectroscopy is “the study of investigation and measurement of the absorption and emission of light or electromagnetic radiation by matter as a function of its wavelength and frequency”. In simple terms, it’s the study of the interaction of light with a matter or substance.
Depending on the nature of the interaction between the energy and material, spectroscopy is divided into subcategories that include: Absorption spectroscopy, emission spectroscopy, elastic scattering and reflection spectroscopy, impedance spectroscopy, resonance spectroscopy, and nuclear spectroscopy.
Spectroscopy is also subdivided depending on the type of radiative energy and the type of interacting material.
In this article, the principle, workings, and applications of protein NMR spectroscopy are discussed. However, before jumping to that, let’s briefly take a look at the basics of NMR spectroscopy.
Nuclear magnetic resonance (NMR) spectroscopy techniques are used to study the molecular structure of chemical compounds by exploiting the magnetic field around their atomic nuclei. This is done by determining the different local electronic environments of atoms like hydrogen, carbon, chlorine, etc in a chemical compound.
It is the only method that produces the 3-D structure of the molecule in the solution phase. The occurring electromagnetic resonance phenomenon provides detailed information about the structure, dynamics, reaction state, and chemical environment of molecules, like protein.
You may read more about the terms, advantages, and disadvantages of NMR spectroscopy in the article “Nuclear Magnetic Resonance Spectroscopy”.
The Principle Of NMR Spectroscopy And Calculations Required To Study The NMR Data Of Proteins (Or Any Other Biomolecule)
The NMR spectroscopy works on the principle of change in the energy state and orientation of atomic nuclei in a magnetic field. The change depends on the presence or absence of electrons around the atomic nuclei of a molecule.
This phenomenon brings all atomic nuclei in the same direction and this is called resonance state. And, the transfer of energy and the state of atomic nuclei is shown by the different levels of signals on the screen.
Further, the signals of the NMR spectra are processed and the amount of energy required to bring the atomic nuclei in the higher state is calculated. Multiple machines are required to yield the structure of the molecule in the solution.
The formula to calculate the required amount of energy to bring the atomic nuclei in their higher state is:
𝚫E = hv
Where = change in energy