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Woda morska i dziury w błonach - Nagroda Nobla z chemii za rok 2003

100%

Pikuła S.

tom 53

nr 3-4

243-249

Summary The Nobel Prize in Chemistry for 2003 was awarded by the Royal Swedish Academy of Sciences in equal parts to two American scientists: Peter Agre from Johns Hopkins University School of Medicine in Baltimore, for the discovery of the water channels, aquaporins, and Roderick MacKinnon from Howard Hughes Medical Institute, the Rockefeller University in New York, for structural and mechanistic studies of the ion channels, especially the potassium and chloride channels. The major breakthrough made by the two scientists in our understanding of water and ion transport processes through biological membranes are briefly described in this editorial note, and the list of their recent selected publications is provided.

GTP-binding properties of the membrane-bound form of porcine liver annexin VI.

51%

Kirilenko A. , Golczak M. , Pikuła S. , Bandorowicz-Pikuła J.

tom 48

nr 4

851-865

Annexin VI (AnxVI) of molecular mass 68-70 kDa belongs to a multigenic family of ubiquitous Ca2+ - and phospholipid-binding proteins. In this report, we describe the GTP-binding properties of porcine liver AnxVI, determined with a fluorescent GTP analogue, 2'-(or 3')-O-(2,4,6-trinitrophenyl)guanosine 5'-triphosphate (TNP-GTP). The optimal binding of TNP-GTP to AnxVI was observed in the presence of Ca2+ and asolectin liposomes, as evidenced by a 5.5-fold increase of TNP-GTP fluorescence and a concomitant blue shift (by 17 nm) of its maximal emission wavelength. Titration of AnxVI with TNP-GTP resulted in the determination of the dissociation constant (Kd) and binding stoichiometry that amounted to 1.3 μM and 1:1 TNP-GTP/AnxVI, mole/mole, respectively. In addition, the intrinsic fluorescence of the membrane-bound form of AnxVI was quenched by TNP-GTP and this was accompanied by fluorescence resonance energy transfer (FRET) from AnxVI Trp residues to TNP-GTP. This indicates that the GTP-binding site within the AnxVI molecule is probably located in the vicinity of a Trp-containing domain of the protein. By controlled proteolysis of human recombinant AnxVI, followed by purification of the proteolytic fragments by affinity chromatography on GTP-agarose, we isolated a 35 kDa fragment corresponding to the N-terminal half of AnxVI containing Trp192. On the basis of these results, we suggest that AnxVI is a GTP-binding protein and the binding of the nucleotide may have a regulatory impact on the interaction of annexin with membranes, e.g. formation of ion channels by the protein.