Nuclear magnetic resonance secondary structure determination

Another method of determining the secondary and tertiary structure of a protein is NMR (nuclear magnetic resonance) spectroscopy. NMR spectroscopy reveals detailed information on specific sites of molecules without having to solve then-entire structure. 

The dependence of the principal components of the nuclear magnetic resonance (NMR) chemical shift tensor of non-hydrogen nuclei in model dipeptides is investigated. It is observed that the principal axis system of the chemical shift tensors of the carbonyl carbon and the amide nitrogen are intimately linked to the amide plane. On the other hand, there is no clear relationship between the alpha carbon chemical shift tensor and the molecular framework. However, the projection of this tensor on the C-H vector reveals interesting trends that one may use in peptide secondary structure determination. Effects of hydrogen bonding on the chemical shift tensor will also be discussed. The dependence of the chemical shift on ionic distance has also been studied in Rb halides and mixed halides. Lastly, the presence of motion can have dramatic effects on the observed NMR chemical shift tensor as illustrated by a nitrosyl meso-tetraphenyl porphinato cobalt (III) complex. 

The determination of the secondary and tertiary structure—that is, the details of the three-dimensional folding of the polypeptide chain of a protein at high resolution—relies on one of two powerful techniques x-ray diffraction analysis of protein crystals and multidimensional high-field nuclear magnetic resonance (NMR) spectroscopy. Both methods provide very detailed structural in-... 

R616 M. Zhang and P. Yang, Determination of the Secondary Structure of Proteins by Nuclear Magnetic Resonance , Huaxue Tongbao, 2000, 12, 26... 

While CD provides a procedure for the rapid determination of secondary structure, it does not provide information in the precise location of the secondary structure within the peptide. This information is more readily obtained from nuclear magnetic resonance (NMR) spectroscopy. 

Secondary structure is difficult to determine directly, although models of a protein can be built using data gathered with nuclear magnetic resonance (NMR) or by X-ray diffraction of protein crystals. Because of these difficulties, unknown secondary structure is often predicted based on what is known about secondary structure of other proteins. 

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