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NMR measurements of proton exchange between solvent and peptides and proteins

100%

Wójcik J., Ruszczyńska K., Zhukov I., Ejchart A.

Cyclic enkephalin-deltorphin hybrids containing a carbonyl bridge: structure and opioid activity

73%

Ciszewska M., Ruszczyńska K., Oleszczuk M., Chung N., Witkowska E., Schiller P., Wójcik J., Izdebski J.

2011

vol. 58

issue 2

225-230

Six hybrid N-ureidoethylamides of octapeptides in which an N-terminal cyclic structure related to enkephalin was elongated by a C-terminal fragment of deltorphin were synthesized on MBHA resin. The synthetic procedure involved deprotection of Boc groups with HCl/dioxane and cleavage of the peptide resin with 45 % TFA in DCM. d-Lys and d-Orn were incorporated in position 2, and Lys, Orn, Dab, or Dap in position 5. The side chains of the dibasic amino function were protected with the Fmoc group. This protection was removed by treatment with 55 % piperidine in DMF, and cyclization was achieved by treatment with bis-(4-nitrophenyl)carbonate. Using various combinations of dibasic amino acids, peptides containing a 17-, 18-, 19- or 20-membered ring structure were obtained. The peptides were tested in the guinea-pig ileum (GPI) and mouse vas deferens (MVD) assays. Diverse opioid activities were observed, depending on the size of the ring. Extension of the enkephalin sequence at the C-terminus by a deltorphin fragment resulted in a change of receptor selectivity in favor of the δ receptor. The conformational propensities of selected peptides were determined using the EDMC method in conjunction with data derived from NMR experiments carried out in water. This approach allowed proper examination of the dynamical behavior of these small peptides. The results were compared with those obtained earlier with corresponding N-(ureidoethyl)pentapeptide amides.

Interaction of three Caenorhabditis elegans isoforms of translation initiation factor eIF4E with mono- and trimethylated mRNA 5' cap analogues.

73%

Stachelska A., Wieczorek Z., Ruszczyńska K., Stolarski R., Pietrzak M., Lamphear B. J., Rhoads R. E., Darżynkiewicz E., Jankowska-Anyszka M.

2002

vol. 49

issue 3

671-682

Translation initiation factor eIF4E binds the m7G cap of eukaryotic mRNAs and mediates recruitment of mRNA to the ribosome during cap-dependent translation initiation. This event is the rate-limiting step of translation and a major target for translational control. In the nematode Caenorhabditis elegans, about 70% of genes express mRNAs with an unusual cap structure containing m32,2,7G, which is poorly recognized by mammalian eIF4E. C. elegans expresses five isoforms of eIF4E (IFE-1, IFE-2, etc.). Three of these (IFE-3, IFE-4 and IFE-5) were investigated by means of spectroscopy and structural modelling based on mouse eIF4E bound to m7GDP. Intrinsic fluorescence quenching of Trp residues in the IFEs by iodide ions indicated structural differences between the apo and m7G cap bound proteins. Fluorescence quenching by selected cap analogues showed that only IFE-5 forms specific complexes with both m7G- and m32,2,7G-containing caps (Kas 2×106 M-1 to 7×106 M-1) whereas IFE-3 and IFE-4 discriminated strongly in favor of m7G-containing caps. These spectroscopic results quantitatively confirm earlier qualitative data derived from affinity chromatography. The dependence of Kas on pH indicated optimal cap binding of IFE-3, IFE-4 and IFE-5 at pH 7.2, lower by 0.4 pH units than that of eIF4E from human erythrocytes. These results provide insight into the molecular mechanism of recognition of structurally different caps by the highly homologous IFEs.

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3 Acta Biochimica Polonica

1 2011

1 2002

1 1999

3 Ruszczyńska K.

2 Wójcik J.

1 Chung N.

1 Ciszewska M.

1 Darżynkiewicz E.

1 Ejchart A.

1 Izdebski J.

1 Jankowska-Anyszka M.

1 Lamphear B. J.

1 Oleszczuk M.

1 Pietrzak M.

1 Rhoads R. E.

1 Schiller P.

1 Stachelska A.

1 Stolarski R.

1 Wieczorek Z.

1 Witkowska E.

1 Zhukov I.

Search results

NMR measurements of proton exchange between solvent and peptides and proteins

Cyclic enkephalin-deltorphin hybrids containing a carbonyl bridge: structure and opioid activity

Interaction of three Caenorhabditis elegans isoforms of translation initiation factor eIF4E with mono- and trimethylated mRNA 5' cap analogues.