RESUMEN
The detailed analysis of conformational space of alpha-conotoxin GI in aqueous solution has been performed on the basis of two-dimensional NMR spectroscopy data using multiconformational approach. As the result, two topologically distinct interconvertible sets of GI conformations (populations of 78% and 22%) have been found. A common feature of the two sets is the Asn4-Cys7 beta-turn. The Gly8 to Tyrll region has a structure of right-handed helical turn in the major set and two sequential bends in the minor one. N-terminus and C-terminus also have different orientations, anti-parallel in the major conformational set and parallel in the minor one. An average pairwise rmsd for backbone heavy atoms is 0.56 A in the major set, 0.23 A in the minor, and 1.85 A between the structures of the two sets. The X-ray structure of GI [Guddat, L. W., Martin, J. A., Shan, L., Edmundson, A. B. & Gray, W. R. (1996) Biochemistry 35, 11329 - 11335] has the same folding pattern as the major NMR set, the average backbone rmsd between the two structures being 0.77 A.
Asunto(s)
Conotoxinas , Venenos de Moluscos/química , Péptidos Cíclicos/química , Secuencia de Aminoácidos , Animales , Cristalografía por Rayos X , Técnicas In Vitro , Espectroscopía de Resonancia Magnética , Modelos Moleculares , Venenos de Moluscos/síntesis química , Péptidos Cíclicos/síntesis química , Conformación Proteica , Soluciones , AguaRESUMEN
Valorphin, an endogenous opioid-like hemoglobin fragment, is cytotoxic for L929 and K562 tumor cells in 10(-7)-10(-13) M concentration range. Because cytolytic effects induced by valorphin in K562 cells are inhibited by naloxone, opioid receptors should be involved in induction of valorphin-mediated tumor cell death. Three distinct cytolytic processes, differing in the onset time and the development time, take place with K562 cells within 10-18 h of incubation with valorphin. All three processes are not associated with apoptotic mechanism of cell death.
Asunto(s)
Adamantano/análogos & derivados , Muerte Celular/efectos de los fármacos , Adamantano/antagonistas & inhibidores , Adamantano/farmacología , Analgésicos Opioides/farmacología , Animales , Apoptosis , Daño del ADN/efectos de los fármacos , Electroforesis en Gel de Agar , Encefalina Metionina/farmacología , Hemoglobinas/química , Humanos , Ratones , Naloxona/farmacología , Receptores Opioides/metabolismo , Células Tumorales CultivadasRESUMEN
A set of synthetic peptides derived from the capsid protein of hepatitis A virus was used to search for B-epitopes. Peptides from the 115-139 region of the VP1 protein, from the 69-99 region of the VP2 protein and peptide 137-150 from the VP3 protein were found to react with monoclonal and polyclonal anti-HAV antibodies. MAPs based on 64-80 and 66-80 fragments of VP3 were reactive as well. Peptides, their conjugates with protein carriers and MAPs were used for antipeptide antibody production. Only free peptide 69-99 from the VP2 protein caused formation of HAV binding antibodies.