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Complex formation reactions of palladium(II)-1,3-diaminopropane with various biologically relevant ligands. Kinetics of hydrolysis of glycine methyl ester through complex formation

100%
El-Sherif A., Shoukry M., El-Bahnasawy R., Ahmed D.
Open Chemistry
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2010
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vol. 8
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issue 4
919-927
EN
The interaction of [Pd(DAP)(H2O)2]2+ (DAP = 1,3-diaminopropane) with some selected bio-relevant ligands, containing different functional groups, were investigated. The ligands used are dicarboxylic acids, amino acids, peptides and DNA constituents. Stoichiometry and stability constants of the complexes formed are reported at 25°C and 0.1 M ionic strength. The results show the formation of 1:1 complexes with amino acids and dicarboxylic acids. The effect of chelate ring size of the dicarboxylic acid complexes on their stability constants is examined. Peptides form both 1:1 complexes and the corresponding deprotonated amide species. DNA constituents form 1:1 and 1:2 complexes. The effect of dioxane on the acid dissociation constants of CBDCA and the formation constant of its complex with Pd(DAP)2+ was reported. The kinetics of hydrolysis of glycine methyl ester bound to [Pd(DAP)(H2O)2]2+ was studied at 25°C and 0.1M ionic strength. [...]
2
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Influence of amino acid sequence on the interaction of short peptides containing 3-[2-(9-anthryl)benzoxazol-5-yl]-alanine with β-cyclodextrin

88%
Mrozek J., Guzow K., Sikorska E., Wiczk W.
Open Chemistry
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2011
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vol. 9
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issue 6
1046-1055
EN
The influence of peptide sequence and Leu chirality in linear and cyclic peptides containing 3-[2-(9-anthryl)benzoxazol-5-yl]alanine on interaction with β-cyclodextrin were studied using fluorescence and NMR spectroscopy. The analysis of enthalpy-entropy compensation effect (α=1.05±0.02 and TΔS00=15.1±0.5 kJ mol−1) indicates that the entropic contribution connected with the solvent reorganization is the major factor governing the peptides-β-cyclodextrin complexation. Moreover, spatial orientation of guest-host molecule depends more than association constant on Leu residue configuration. However, the cyclization of the peptide chain substantially decrease the association constant with β-CD. An analysis of 2D NMR spectra reveals that inclusion complex is formed by penetration of cyclodextrin cavity from wider and narrow rims by anthryl group in the case of Box(Ant)-SPKL or anthryl and Leu residues for Box(Ant)-SPK(D)L analogue. [...]
3
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Fully automated chip-based nanoelectrospray combined with electron transfer dissociation for high throughput top-down proteomics

88%
Flangea C., Schiopu C., Capitan F., Mosoarca C., Manea M., Sisu E., Zamfir A.
Open Chemistry
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2013
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vol. 11
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issue 1
25-34
EN
The conventional protocol for protein identification by electrospray ionization mass spectrometry (MS) is based on enzymatic digestion which renders peptides to be analyzed by liquid chromatography-MS and collision-induced dissociation (CID) multistage MS, in the so-called bottom-up approach. Though this method has brought a significant progress to the field, many limitations, among which, the low throughput and impossibility to characterize in detail posttranslational modifications in terms of site(s) and structure, were reported. Therefore, the research is presently focused on the development of procedures for efficient top-down fragmentation of intact protein ions. In this context, we developed here an approach combining fully automated chip-based-nanoelectrospray ionisation (nanoESI), performed on a NanoMate robot, with electron transfer dissociation (ETD) for peptide and top-down protein sequencing and identification. This advanced analytical platform, integrating robotics, microfluidics technology, ETD and alternate ETD/CID, was tested and found ideally suitable for structural investigation of peptides and modified/functionalized peptides as well as for top-down analysis of medium size proteins by tandem MS experiments of significantly increased throughput and sensitivity. The obtained results indicate that NanoMate-ETD and ETD/CID may represent a viable alternative to the current MS strategies, with potential to develop into a method of routine use for high throughput top-down proteomics.
4
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Altered membrane amino acids composition in human colorectal cancer tissue

88%
Szachowicz-Petelska B., Sulkowski S., Figaszewski Z.
Open Chemistry
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2012
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vol. 10
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issue 4
1245-1252
EN
Cancer transformation is characterized by changes in cell metabolism, which can alter the structure and function of cell membrane components, including integral membrane proteins. Qualitative and quantitative estimations of integral membrane protein are necessary for studies aimed at understanding their modifications under pathological conditions. Herein, we used a high-performance liquid chromatography (HPLC)-based approach that involved selective hydrolysis of isolated tissue cell membrane proteins to peptides, resolution by chromatography and determination of the amino acid content (phenylalanine (Phe), tyrosine (Tyr), cysteine (Cys) and lysine (Lys)) in individual peptides. The results demonstrate decrease in peptide levels and their amino acids content in integral membrane proteins in human colorectal cancer tissue. Therefore, cancer transformation causes a decrease in the levels of integral membrane proteins, which may in turn lead to an increase in the levels of other charged molecules on the cell surface, such as phospholipids. It might lead to the reconstruction and functional rearrangement of the cell membrane, for example: the permeability, electric properties, fluidity etc. [...]
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