Wyniki wyszukiwania - Biblioteka Nauki

Nowa wersja platformy, zawierająca wyłącznie zasoby pełnotekstowe, jest już dostępna.
Przejdź na https://bibliotekanauki.pl

Ograniczanie wyników

Znaleziono wyników: 5

Liczba wyników na stronie

Wyniki wyszukiwania

Sortuj według:

Ogranicz wyniki do:

Spektroskopia magnetycznego rezonansu jadrowego w wyznaczaniu budowy bialek

100%

Ejchart A.

tom 53

nr 3-4

263-270

Strategie NMR wyznaczania struktur białek w roztworze

100%

Ejchart A.

Wiadomości Chemiczne

2005

tom [Z] 59, 1-2

23--45

A number of reasons have hindered the use of NMR spectroscopy as a tool for the protein structure determination. Recently, the advance in the NMR equipment, spectral techniques and isotope labelling has resulted in an enormous growth of NMR-determined protein structures. After a brief presentation of protein structure and conformation several types of NMR-derived constraints and the characteristic features of chemical shifts in proteins are discussed. Short-range, distance and dihedral angle constraints are valuable, but cumulative errors can appear when succesive constraints are used to determine spatial relationship of remote parts of a protein. Therefore, long-range constraints derived from residual dipolar couplings are highly complementary to the short-range constraints. Modern strategies to the NMR-based protein structure determination depend on the size of studied biomolecules. Small proteins (Mcz< 10 kDa) can be studied with the use of two-dimensional (2D) 1H NMR techniques. Medium size proteins (Mcz < 30 kDa) require double isotopic labeling 15N/13C and multidimensional (3D and 4D) heteronuclear techniques. There is no well established strategy to the structure determination of large proteins (Mcz > 30 kDa) yet. The most promising approaches take advantage of triple isotopic labeling 15N/13C/2H and the transverse relaxation optimized spectroscopy (TROSY), both resulting in the reduction of signal width.

Non-classic constraints in protein structure determination

100%

Ejchart A.

2000

tom Vol. 48, No. 1

1-11

Recently, three new types of structural constraints have been introduced into the procedures of protein structure determination. Application of residual dipolar cou-plings, interference effects, and dependence of heteronuclear relaxation times on rotational diffusion anisotropy opens new perspectives for the functional and structural NMR studies of proteins.

Wpływ częściowego uporządkowania orientacji cząsteczek na ich widma NMR dużej zdolności rozdzielczej

63%

Ejchart A. , Gryff-Keller A.

Wiadomości Chemiczne

2000

tom [Z] 54, 11-12

949-969

Molecules of solute in the liquid phase can display partial orientation owing to the interaction of an anisotropic magnetic susceptibility tensor with an external magnetic field or/and to the interaction with anisotropic liquid crystal solvent. In the latter case orientation of the solvent molecules is caused by the magnetic field as well. Formal, statistic description of the solute molecular orientation is identical in both cases and it has been demonstrated without recalling to the Wigner rotation matrices. Since the orientation of solute molecules is not averaged out due to the rotational diffusion completely, several interactions, additional to the isotropic liquid phase, manifest in the NMR spectra, namely, dipolar nad quadrupolar interactions as well as anisotropic parts of chemical shifts (screening) and spin-spin couplings. Therefore, a number of structural molecular parameters, which depend on those interactions, become accessible. Determination of very accurate geometries of small organic molecules and the accuracy improvement of the NMR-derived structures of biomolecules are the most frequent applications of the NMR studies in anisotropic phases. Analysis of the NMR spectra of 3,5-dichlorphenylacethylene in the nematic solvent ZLI1169 has been presented as an example of the liquid crystal solvent application.

Evaluation of the SOS chromotest for detection of genotoxic drugs

51%

Marczewska J. , Chlopkiewicz B. , Ejchart A. , Koziorowska J.

1993

tom 42

nr 2