Academic > Health Sciences > Download, free read

Nuclear Magnetic Resonance of Biological Macromolecules, Part A by Thomas L. James download in iPad, ePub, pdf

In total correlation spectroscopy, the alpha and all the other protons are able to transfer magnetization to the beta, gamma, delta, epsilon if they are connected by a continuous chain of protons. The process results in an ensemble of structures that, if the data were sufficient to dictate a certain fold, will converge. Other things being equal, higher-dimensional experiments will take longer than lower-dimensional experiments. However, in large molecules such as proteins the number of resonances can typically be several thousand and a one-dimensional spectrum inevitably has incidental overlaps.

Another approach uses the chemical shifts to generate angle restraints. The structures will converge only if the data is sufficient to dictate a specific fold. This problem becomes greater as the protein becomes larger, so homonuclear nuclear magnetic resonance is usually restricted to small proteins or peptides. The process of population relaxation refers to nuclear spins that return to thermodynamic equilibrium in the magnet. The continuous chain of protons are the sidechain of the individual amino acids.

The structures will convergeAnother approach uses the

In this way, measurements of relaxation times can provide information of motions within a molecule on the atomic level. Each window is focused on the nitrogen chemical shift of that amino acid. By determining the orientation of a sufficient amount of bonds relative to the external magnetic field, the structure of the protein can be determined. To acknowledge this fact is really important because it means that the model could be a good or bad representation of that experimental data.

Protein dynamics In addition to structures, nuclear magnetic resonance can yield information on the dynamics of various parts of the protein. Usually several of these experiments are required to resolve overlap in the carbon dimension. Thus, the results obtained from nitrogen relaxation measurements may not be representative for the whole protein.