Andrzej Temeriusz

Thiazolidine-4(R)-carboxylic acids derived from sugars: Part I, C-2-epimerisation in aqueous solutions

Abstract Reactions of l -cysteine ( 1 ) with l -xylose, d -ribose, d -lyxose, d -arabinose, d -glucose, l -rhamnose, and l -fucose in aqueous ethanol yielded crystalline 2( S )-(polyhydroxyalkyl)thiazolidine-4( R )-carboxylic acids. Likewise, glycolaldehyde and l -glyceraldehyde, d -xylose, l -arabinose, d -mannose, d -galactose, and d -fucose gave crystalline 2( R ),4( R ) epimers. The reaction of 1 and d -glyceraldehyde gave a syrupy mixture of 2( S ),4( R ) and 2( R ),4( R ) compounds. The same substrates, but with no ethanol present, gave the 2( S ),4( R ) epimers for glycolaldehyde, l -xylose, l -fucose, and l -arabinose, and the 2( R ),4( R ) epimers for d -lyxose, l -rhamnose, d -mannose, d -galactose, and d -fucose. The reactions of d -ribose, d -arabinose, d -xylose, and d -glucose gave syrupy mixtures of epimers. The crystalline reaction products, when dissolved in water, undergo rapid epimerisation as reflected by mutarotation and changes in the 1 H- and 13 C-n.m.r. spectra.

13C CP MAS and high-resolution 1H, 15N NMR study of ureido sugars

Abstract Ureido sugars with eight various alkyl groups at N-3 were studied by means of 1H, 13C, and 15N NMR spectroscopy in CDCl3 solution and a 13C CP MAS technique in the solid state. The analysis of chemical shifts and coupling constants suggests the Z,Z-anti conformation of the ureido part of molecule. Differences of δ between the liquid and solid state are observed for the C-2, C-6, and OMe carbon atoms of the d -glucopyranose moiety, as well as the splitting of the anomeric carbon C-1 and OMe signals. The possibility of various conformations in the solid state are discussed. IR spectra of solid ureido sugars indicate that both NH groups are involved in hydrogen bonding. On the other hand, dilution with CDCl3 followed by 1H NMR showed that N-1-H forms a stronger bond than N-3-H.

Effects of Cyclodextrin Derivatives on the Catalytic Activity of Tyrosine Phenol-Lyase

The impact of permethylated α-, β-, γ-cyclodextrin (TMα-CD, TMβ-CD, TMγ–CD, respectively) on TPL-catalysed decomposition of L-tyrosine was investigated by means of spectrophotometric measurements. The inhibitory effects of TM-CDs on the catalytic activity of the enzyme were shown. This phenomenon is supposed to be connected with the host–guest complex formation. CDs were found to have impact on maximal velocity and on Michaelis constant of described catalysis.

1H-NMR studies on association of mRNA cap-analogues with tryptophan-containing peptides.

1H-NMR spectroscopy was applied to a study of the mode of interaction, in aqueous medium in the pH range 5.2-8.5 and at low and high temperatures, between several mono- and dinucleotide analogues of the mRNA cap m7GpppG and a selected tripeptide Trp-Leu-Glu, and a tetrapeptide Trp-Glu-Asp-Glu, the sequence of which corresponds to one of the suspected binding sites in the mRNA cap-binding protein (CBP). A program, GEOSHIFT, was developed, based on ring-current anisotropy theory, for analysis of experimentally observed changes in chemical shifts accompanying interactions between aromatic heterocyclic rings. This permitted quantitative evaluation of stacking interactions between the m7G cap and the tryptophan indole ring, and the relative orientations of the planes of the two rings, spaced about 3.2 angstroms apart. The structures of the stacked complexes were determined. In particular, stacking between m(2,2,7)3G (which has no free amino group for hydrogen bonding) and the indole ring is weaker and quite different from that between m7G and m(2,7)2G and indole. With the dinucleotide cap-analogues, only the m7G component stacks with the indole ring, without disruption of intramolecular stacking. In contrast to numerous earlier reports, the calculated stacking interactions are quantitatively in accord with the values derived from fluorescence measurements. It also has been shown that the positively charged (cationic) form of m7G stacks much more efficiently with the indole ring than the zwitterionic form resulting from dissociation of the guanine ring N1H (pKa approximately 7.3).

Single-crystal and powder X-ray diffraction and solid-state 13C NMR of p-nitrophenyl glycopyranosides, the derivatives of D-galactose, D-glucose, and D-mannose

The X-ray diffraction patterns, (13)C CP MAS NMR spectra, and powder X-ray diffraction analyses were obtained for selected p-nitrophenyl glycosides: alpha- and beta-D-galactopyranosides (1 and 2), alpha- and beta-D-glucopyranosides (3 and 4), and alpha- and beta-D-mannopyranosides (5 and 6). In X-ray diffraction analysis of 1 and 2, characteristic shortening and lengthening of selected bonds were observed in the molecules of 1 due to anomeric effect, and in the crystal lattice of 1 and 2, hydrogen bonds of complex network were detected. In the crystal asymmetric unit of 1 there were two independent molecules, whereas in 2 there was one molecule. For 1 and 3-6 the number of resonances in solid-state (13)C NMR spectra exceeded the number of the carbon atoms in the molecules, while for 2 there were distinct singlet resonances in its solid-state NMR spectrum. Furthermore, the powder X-ray diffraction (PXRD) performed for 1-3 and 5 revealed that 1, 3, and 5 existed as single polymorphs proving that the doublets observed in appropriate solid-state NMR spectra were connected with two non-equivalent molecules in the crystal asymmetric unit. On the other hand 2 existed as a mixture of two polymorphs, one of them was almost in agreement with the calculated pattern obtained from XRD (the difference in volumes of the unit cells), and the subsequent unknown polymorph existed in small amounts and therefore it was not observed in solid-state NMR measurements.

Synthesis and monolayer behavior of amphiphilic per(2,3-di-O-alkyl)-α- and β-cyclodextrins and hexakis(6-deoxy-6-thio-2,3-di-O-pentyl)-α-cyclodextrin at an air–water interface

A synthesis of amphiphilic per(2,3-di-O-alkyl)-α- and β-cyclodextrins and hexakis(6-deoxy-6-thio-2,3-di-O-pentyl)-α-cyclodextrin and their monolayer behavior on a water surface is presented. Long alkyl chains were introduced by a treatment of the per(6-O-tert-butyldimethylsilyl) derivatives with an appropriate alkyl iodide in dimethylformamide in the presence of sodium hydride. A standard desilylation procedure followed by an iodination reaction afforded per(6-deoxy-6-iodo) analogues. In the latter reaction step, sulphur containing groups were introduced by nucleophilic substitution of the iodine with benzothiolate ion in dimethylformamide. The hexakis(6-deoxy-6-S-benzyl-2,3-di-O-pentyl)-α-cyclodextrin was transformed into extremely interesting hexakis(6-deoxy-6-thio-2,3-di-O-pentyl)-α-cyclodextrin. The surface pressure−mean molecular area (π−A) isotherms indicated that the synthesised amphiphilic cyclodextrin derivatives were capable of forming stable monolayers at the air–water interface. The shapes of the isotherms were typical for solid-like monolayers except for hexakis(6-deoxy-6-thio-2,3-di-O-pentyl)cyclomaltohexaoses which formed a more liquid monolayer.

13C CP MAS NMR and crystal structure of methyl glycopyranosides

The X-ray diffraction analysis, (13)C CP MAS NMR spectra and powder X-ray diffraction patterns were obtained for selected methyl glycosides: alpha- and beta-d-lyxopyranosides (1, 2), alpha- and beta-l-arabinopyranosides (3, 4), alpha- and beta-d-xylopyranosides (5, 6) and beta-d-ribopyranoside (7) and the results were confirmed by GIAO DFT calculations of shielding constants. In X-ray diffraction analysis of 1 and 2, a characteristic shortening and lengthening of selected bonds was observed in molecules of 1 due to anomeric effect and, in crystal lattice of 1 and 2, hydrogen bonds of different patterns were present. Also, an additional intramolecular hydrogen bond with the participation of ring oxygen atom was observed in 1. The observed differences in chemical shifts between solid state and solution come from conformational effects and formation of various intermolecular hydrogen bonds. The changes in chemical shifts originating from intermolecular hydrogen bonds were smaller in magnitude than conformational effects. Furthermore, the powder X-ray diffraction (PXRD) performed for 4, 5 and 7 revealed that 7 existed as a mixture of two polymorphs, and one of them probably consisted of two non-equivalent molecules.

Synthesis and characterization by 13C-CP-MAS- and high resolution 1H-, 13C-NMR of new ureido sugars, derivatives of methyl 2-amino-2-deoxy-β-d-glucopyranose and dipeptides

Abstract Dipeptide ethyl and benzyl esters were used as amination agents in reaction with methyl 3,4,6- tri -O- acetyl-2-deoxy-2-(4-nitrophenoxycarbonylamino)-β- d -glucopyranoside(1) . Ten new ureido sugars, derivatives of GlyAla, AlaGly, AlaAla, GlyVal, ValGly, LeuGly, PheGly, GlyPhe, and AlaPhe were obtained. The new ureido sugars were studied by means of 1 H- and 13 C-NMR spectroscopy in solution, and 13 C-CP-MAS-NMR in the solid-state. Dipeptide ethyl and benzyl esters were used as amination agents in reaction with methyl 3,4,6,-tri-O-acetyl-2-deoxy-2-(4-nitrophenoxycarbonylamino)-β- d -glucopyranoside. Ten new ureido sugars, derivatives of GlyAla, AlaGly, AlaAla, GlyVal, ValGly, LeuGly, PheGly, GlyPhe, and AlaPhe were obtained. The new ureido sugars were studied by means of 1 H and 13 C NMR spectroscopy in solution, and 13 C CP MAS NMR in the solid-state.

13C CP MAS and high-resolution 1H, 13C, 15N NMR study of new ureido sugars, derivatives of 2-amino-2-deoxy-β-d-glucopyranose and l-amino acid

Abstract Ureido sugars with seven various l -amino acid ester residues were studied by means of 1 H, 13 C, and 15 N NMR in solution and 13 C CP MAS in the solid state. The chemical shifts and coupling constants in the 1 H, 13 C, and 15 N NMR spectra indicated that the replacement of one amino acid residue by another has no significant effect on the conformation of glucopyranose moiety. The shielding of nitrogen linked to glucose does not change, whereas the shielding of nitrogen of amino acid residues increases in the order Ala α . 13 C CP MAS spectra of 1–5 were recorded and assigned. The C-3 and C-6 carbons of sugar, the carbonyl carbons of the ureido bridge, and the carbons of the amino acid ester residues are deshielded in the solid state compared to the respective values for CDCl 3 solution owing to the loss of conformational flexibility and different intermolecular interactions.

Crystal Structure and Solid State NMR Analysis of N-(Methyl 3,4,6-Tri-O-Acetyl-2-Amino-2-Deoxy-β-D-Glucopyranoside)-N'Carbamoyl-D-Valine Ethyl Ester

Abstract The X-ray diffraction analysis of N-(methyl 3,4,6-tri-O-acetyl-2-amino-2-deoxy-β-D-glucopyranoside)-N′-carbamoyl-D-valine ethyl ester has been performed establishing that molecules are associated by two types of NH…O hydrogen bonds. The N-1-H forms an intermolecular hydrogen bond with carbonyl oxygen, and the N-3-H forms a hydrogen bond with the anomeric oxygen, with distances 2.927(6) A, and 3.063(7) A, respectively. The urea moiety of the molecule is in the anti-Z,Z conformation. The signals in the 13C CP MAS NMR spectrum are neither multiplied nor split, confirming that there is one molecule in the crystal asymmetric unit. The difference in chemical shifts between solid and solution spectra are significant for C-2, C-3 and OMe group of D-glucose moiety (1.7, 2.6 and 2.9 ppm respectively) and for NCON, Cα and Cβ D-valine carbon atoms.