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Recent research into the structure and properties of proteins and peptides as physiologically active diet components has spurred a new interest in the isolation and investigation of bioactive peptides of animal, plant and microbiological origin. The isolation and separation of protein and peptide mixtures requires advanced procedures. It usually involves a multi-stage separation process on chromatographic columns with various packing. Immo- bilised Metal Ion Affinity Chromatography (IMAC) is frequently used in the complex process of obtaining peptide fractions. Affinity Chromatography (IMAC) relies on the specific interactions between amino acids, their reactive groups in proteins and peptides and „transitory” metal ions, in particular Cu2+. Those ions are immobilised by the chelating compound on the bed, forming specific adsorbents which bind proteins and peptides. The aim of this study was to determine whether o-phosphoserine (OPS) can be used for the immobilization of copper ions on Sephadex G25 during the separation of peptides and proteins isolated from string beans. Frozen pods of dwarf, green-podded string bean cv. Fana were used in the study. Peptide were extracted from well-homogenized string bean pods with tris-HCl buffer (pH 7.5), from which high molecular weight proteins were isolated with methanol, acetone, 20% trichloroacetic acid and the Magnafloc M-22S cation flocculant. The protein and peptide content of the separated fractions was determined. The peptide content depended on the type of extract from which high molecular weight proteins were isolated. The results obtained by using OPS as a chelating agent in the separation of string bean can be recommended for analysis of plant peptides.
Recent years have witnessed growing interest in research on the structure and properties of proteins and peptides as physiologically active dietary components. The above has spurred a new interest in the isolation of animal, plant and microbiological peptides and investigation of their biological activity. The isolation and separation of protein and peptide mixture is not an easy procedure. Immobilised Metal Ion Affinity Chromatography (IMAC) is increasingly often used in this process. Affinity chromatography relies on the specific interactions between amino acids, their reactive groups in peptides and metal ions. The objective of this study was to determine whether copper and nickel ions can be used for the separation of peptides isolated from string beans than had been blanched and heated in a microwave oven. In this study, peptides extracted with 1% trichloroacetic acid (TCA) from string beans that had been blanched and heated in a microwave oven, were separated by chromatography on columns with copper and nickel ions immobilised through iminodiacetic acid (IDA). Peptide concentrations of the separated fractions were determined. Peptides found in string beans had similar affinity for metal ions in the Cu > Ni sequence, with selectivity in the Ni > Cu sequence. Microwave heating of string beans decreases the peptide content of extracts isolated with 1% TCA. The resulting changes are dependent on the duration of the process and the type of heating medium. Affinity chromatography with the use of metal ions immobilized to iminodiacetic acid (IDA)-Sephadex G-25 may be successfully used for the separation of peptides isolated from string beans.
The location and nature of the linkage between peptidoglycan and oligoglucans in the cell wall of Mesorhizobium loti HAMBI 1148 have been defined by the analysis of nitrous acid deamination of peptidoglycan glucosaminyl residues. The MurNH2-Glcn fraction was obtained after converting deaminoacylated and N-deacetylated muramyl residues in the cell wall preparation to lactam forms which were stable during subsequent deamination, followed by reduction and opening of the lactams. GC/MS analysis of this material, subjected to partial hydrolysis and reduction or to methanolysis followed by peracetylation, confirmed the presence of glucosyl residues glycosidically attached to muramic acid. The MALDI-TOF spectroscopic analysis of the deaminated material also revealed the presence of [M-H]- or [M+Na-2H]- ions representing fragments containing muramic acid with one to three linked glucose residues. The analysis of fully methylated neutral oligosaccharides released from the peptidoglycan with lysozyme followed by borohydride reduction showed the presence of di- and trisaccharides lacking the reducing end.
W pracy określono wpływ stopnia uwodnienia sacharozy amorficznej i jej mieszanin z agarem na parametry ich przemian fazowych (temperatura przemiany szklistej, temperatura i ciepło krystalizacji, temperatura i ciepło topnienia). Stwierdzono, że wraz ze wzrostem zawartości wody, we wszystkich badanych materiałach, nastąpiło obniżenie temperatury i ciepła krystalizacji oraz temperatury i ciepła topnienia. 1 % dodatek agaru wpłynął na opóźnienie procesu krystalizacji sacharozy i spowodował ponad dwukrotny wzrost wartości ciepła topnienia w porównaniu do czystej sacharozy amorficznej.
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