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Biomedical subjects

E N Zvonkova

Publications and source records attributed to E N Zvonkova.

12 recordsLinked to original sources
PubMed1995

Isolation of individual amino acids from various microbiological sources using reversed-phase high-performance liquid chromatography.

A new method for the preparative isolation of individual amino acids on a milligram scale based on reversed-phase high-performance liquid chromatography (RP-HPLC) after pre-column derivatization with carbobenzoxychloride (Z-Cl) has been developed. The chromatographic procedure was tested by the investigation of jack bean urease hydrolysate. The method has been applied to the preparative separation of Z-amino acids (from 10 up to 16) obtained from protein hydrolysates of various sources (green microalgae, blue-green algae, halophilic and methylotrophic microorganisms) and was proved to be reliable by the separation of deuterated amino acids (enrichment 97-99%) from Methylobacillus flagellatum (due to the bioconversion of CD3OD and D2O). Independent of the biological source of the protein, the amino acids were isolated with high recovery (from 68% up to 89%) and chromatographic purity (from 96% up to 99%). The method was also applied for the isolation of phenylalanine and leucine excreted by amino-acid overproducing microorganisms.

Amino Acids↗
PubMed1995

[Synthesis of stearoyl derivatives of proline-containing hydrophobic peptides].

Hydrophobic stearoyl derivatives of proline-containing di- and tripeptides and their deuterated analogs were synthesized. It was shown by NMR spectroscopy that cis-trans-equilibrium around an X-Pro peptide bond is displaced towards trans-conformers for compounds containing a Ste-Pro fragment as opposed to the compounds containing Boc-Pro or Gly-Pro fragments.

Amino Acid Sequence↗
PubMed1993

[Ganglioside GM3 from horse erythrocytes: structure and effect on cell proliferation].

An increase of the mouse fibroblast proliferation by ganglioside GM3 from equine erythrocytes is described. The structure of GM3 has been established on the basis of chemical methods, enzymatic degradation, GC-MS, as well as plasma desorption mass spectrometry and HPLC of 9-anthrylmethyl esters of gangliosides to characterize the long-chain base composition. The oligosaccharide moiety includes an N-glycolylneuraminic acid residue, whereas the main components of the lipid moiety are 20:1 sphingosine and 24:0 fatty acids.

Animals↗
PubMed1992

[Protein motifs and their structure-functional role].

The review deals with repeating fragments of amino acid sequences, so-called "motifs", that are important in maintaining structural integrity and/or function of various proteins, especially those interacting with phospholipid aggregates. The occurrence of Phe-Leu-Gly motif characteristic for the amino acid sequence of the primate immuno-deficiency viruses fusion peptides is analysed in various proteins, as well as tripeptide fragments of general formula Xaa-Xah-Gly (Xaa-Phe, Tyr; Xab-hydrophobic amino acids Ala, Val, Leu, Ile) homologous to the above motif and retro-sequences Gly-Xab-Xaa. These tripeptide repeats are characteristic for the amino acid sequences of complex membrane proteins, viral envelope proteins, proteinases and proteins connected with energy transfer or interacting with lipids. These repeats are frequently met in conservative regions of amino acid sequences, in sites readily accessible for other molecules at the boundary of or between structured fragments, this being due to the backbone semi-coiled form's preference in the given amino acid fragment. This protein motif appears to play an important role at the initial stages of the large protein's interaction with the phospholipid membrane.

Amino Acid Sequence↗
PubMed1991

[Synthesis of the tripeptide glycyl-L-leucyl-L-phenylalanine and its analogs].

Peptide Gly-L-Leu-L-Phe and its derivatives were synthesized by the C-end elongation utilizing DCC/HOBT technique and by enzymatic route with the help of papain using esters of N-benzyloxycarbonyl-glycine and -L-leucine as acyl donors have been suggested. The chemical, similarly to the enzymatic, synthesis was not accompanied by racemization. Conditions for HPLC separation and preparative isolation of the enzymatic reaction products were developed.

Chromatography, High Pressure Liquid↗
PubMed1987

[Synthesis of phosphonate analogs of sphingomyelins and preparation of an affinity sorbent for sphingomyelinase purification].

Phosphonate analogues of 2-N-stearoyl- (I) and 2-N-(undec-10-enoyl)-sphingomyelins (II) have been synthesised. Compound (II) was used as a starting product for preparation of a sorbent for sphingomyelinase affinity chromatography. The double bond of the unsaturated undec-10-enoyl moiety of the phosphonate analogue (II) was oxidized, and the modified (II) was coupled to amino-Toyopearl HW-65 to give a sorbent containing 4 mumoles of ligand per milliliter of the swollen resin.

Bacillus cereus↗
PubMed1983

[Semisynthetic cerebrosides].

Psychosine prepared from bovine brain cerebroside was used for synthesis of galactosphingolipids with DL-, D-, or L-2-hydroxyhexadecanoic acids and 6-(2'-anthroyl) hexanoic acid. Psychosine was N-acetyl with p-nitrophenyl 2-acetoxyhexadecanoates in the presence of hydroxybenzotriazole to give cerebrosides. The 6-(2'-anthroyl)hexanoic acid reaction with psychosine was effected via its acyl chloride.

Animals↗