Authors:Cristina Sánchez López, C. Barriga, A. Rodríguez, L. Franco, M. Rivero, and J. Cubero
, Cronenberger L, Pacheco H: Diurnal variations of S-adenosyl-L-methionine and adenosine content in the rat pineal gland. Life Sci. 35(6), 589–596 (1984)
Diurnal variations of S-adenosyl-L-methionine
Authors:G. Meyer, A. Osterholz, and H. Hundeshagen
Radio high pressure liquid chromatography (radio-HPLC) is the method of choice for quality control of radiopharmaceuticals
labelled with short lived isotopes. Our preparations of “no carrier added”11C-labelled palmitic acid and L-methionine are both designed to end with a HPLC separation on either silica gel or C-18 reversed
phase material. Since the crude reaction mixtures contain milligram amounts of inactive substrate materials, both separations
must be carried out at preparative scale. Nevertheless they are performed in less than 10 min. The most critical factor for
the separation of11C-palmitic acid from the main by-product pentadecane is the solvent composition: while the11C-L-methionine separation is especially sensitive to pH variations.
Authors:Franco Cataldo, Pietro Ragni, Susana Iglesias-Groth, and Arturo Manchado
The sulphur-containing proteinaceous amino acids l-cysteine, l-cystine and l-methionine were irradiated in the solid state to a dose of 3.2 MGy. This dose corresponds to that delivered by radionuclide
decay in a timescale of 1.05 × 109 years to the organic matter buried at a depth >20 m in comets and asteroids. The purity of the sulphur-containing amino acids
was studied by differential scanning calorimetry (DSC) before and after the solid state radiolysis and the preservation of
the chirality after the radiolysis was studied by chirooptical methods (optical rotatory dispersion, ORD) and by FT-IR spectroscopy.
Although the high radiation dose of 3.2 MGy delivered, all the amino acids studied show a high radiation resistance. The best
radiation resistance was offered by l-cysteine. The radiolysis of l-cysteine leads to the formation of l-cystine. The radiation resistance of l-methionine is not at the level of l-cysteine but also l-methionine is able to survive the dose of 3.2 MGy. Furthermore in all cases examined the preservation of chirality after
radiolysis was clearly observed by the ORD spectroscopy although a certain level of radioracemization was measured in all
cases. The radioracemization is minimal in the case of l-cysteine and is more pronounced in the case of l-methionine. In conclusion, the study shows that the sulphur-containing amino acids can survive for 1.05 × 109 years and, after extrapolation of the data, even to the age of the Solar System i.e. to 4.6 × 109 years.
Authors:Debasis Das, Animesh Sahana, Raja Saha, Pijush Kundu, and Subrata Laskar
A new ligand has been synthesized by anchoring anthracene to l
-methionine. The ligand enables easy identification of amino acids on thin-layer chromatography plates by developing distinguishable colors. This paper deals with the detailed synthesis, characterization, and application of the new ligand. Estimation of binding constants of this new ligand with different amino acids are also reported. A theoretical calculation (
) has been performed to investigate interaction of the ligand with the amino acid.
Direct resolution of enantiomers of (RS)-ketorolac was achieved by thin-layer chromatography on silica gel plates using enantiomerically pure L-tryptophan, L-valine, L-methionine, and L-histidine as chiral additive in the stationary phase. The solvent system (acetonitrile, methanol water, and chloroform) with different ratios was successful in resolving the enantiomers. Spots were detected by use of iodine vapor. The detection limit was 0.4 µg mL−1 for each enantiomer of (RS)-ketorolac. The native enantiomers were isolated and characterized.
Authors:Ashraf El-Sayed, Salwa Khalaf, Gamal Abdel-Hamid, and Mohamed El-Batrik
The potency for production of cystathionine γ-lyase (CGL) by the fungal isolates was screened. Among the tested twenty-two isolates, Aspergillus carneus was the potent CGL producer (6.29 U/mg), followed by A. ochraceous (6.03 U/mg), A. versicolor (2.51 U/mg), A. candidus (2.12 U/mg), A. niveus and Penicillium notatum (2.0 U/mg). The potent six isolates producing CGL was characterized morphologically, A. carneus KF723837 was further molecularly characterized based on the sequence of 18S–28S rDNA. Upon sulfur starvation, the yield of A. carneus extracellular CGL was increased by about 1.7- and 4.1-fold comparing to non-sulfur starved and L-methionine free medium, respectively. Also, the uptake of L-methionine was duplicated upon sulfur starvation, assuming the activation of specific transporters for L-methionine and efflux of CGL. Also, the intracellular thiols and GDH activity of A. carneus was strongly increased by S starvation, revealing the activation of in vivo metabolic antioxidant systems. Upon irradiation of A. carneus by 2.0 kGy of γ-rays, the activity of CGL was increased by two-fold, regarding to control, with an obvious decreases on its yield upon further doses. Practically, CGL activity from the solid A. carneus cultures, using rice bran as substrate, was increased by 1.2-fold, comparing to submerged cultures, under optimum conditions.
The method developed for the determination of the optical purity of L-selenomethionine-75Se is based on the conversion of the mixture of L-and D-amino acids into the diastereoisomeric derivatives by reaction with
(−)-camphorsulphonyl chloride. The diastereoisomeric derivatives are separated by means of thin layer chromatography. From
the ratio of the radioactivities of the two spots on the chromatogram, the optical purity is calculated, and given in % D.
For a sample of L-methionine-14C the following value was found: 0.53±0.05 (S.D. of mean, n=7). For a sample of DL-methionine-14C the percentage of D found, was: 48.5±0.5 (S. D. of mean, n=7). Of 30 different samples of L-selenomethionine-75Se the percentages of D-isomer were determined in duplicate. From the 30 differences between duplicates the S. D. of a single
measurement is calculated to be 0.2.
Authors:Lj. Glavaš-Obrovac, T. Klapec, I. Karner, and M. L. Mandić
Studies performed so far on different human carcinoma cell lines, as well as numerous case-control and epidemiological studies have given proof to the protective effects of selenium against cancer. However, the anticancer properties of selenium are site-specific. The aim of this work was to evaluate the cytotoxic effect of selenium against CaCo2 human colon carcinoma cells, and SW620 lymph node metastasis of colon carcinoma cell line. Three selenium compounds, seleno-DL-cystine (SeC), seleno-L-methionine (SeM) and sodium selenite were used. Initial number of cells was 210 4 and the cells were incubated for 72 h with the aforementioned Se compounds at 10, 100 and 1000 µmol Se concentrations. Cytotoxicity was measured by the MTT cell survival assay. In the present study, decreased viabilities of both CaCo2 and SW620 cells were established following the treatment with selenite, SeC, and SeM. At 10 µmol Se levels all three chemical forms exerted a more or less anticipated cytotoxic effect with viability decreases ranging from 22 to 37%. However, the other two levels of 100 and 1000 µmol Se did not exhibit an expected proportional rise in cytotoxic effect compared to 10 µmol, which warrants further research on the reasons for increased resistance of these cells. Cell morphology also indicates that investigated Se forms induced apoptotic cell death in both cell lines. The results confirm the applicability of Se in the prevention and treatment of the investigated cancer sites.
Authors:S. Hussein, É. Gelencsér, M. Polgár, and György Hajós
Buffalo and cow milk caseins were submitted to hydrolysis either with á -chymotrypsin or with pepsin. Enzymatic peptide modification (EPM) was carried out by using L-methionine ethyl ester in the reaction mixture. As catalyst, á -chymotrypsin or pepsin was used. The incorporation of methionine in to the peptide chains in the presence of á -chymotrypsin showed an optimum value at 0.14 g Met added to the reaction mixture/1 g hydrolysate in both cases. In the case of pepsin used as catalyst, the optimal Met-enrichment was at 0.14 g Met added to the reaction mixture/1 g buffalo casein hydrolysate and at 0.34 g Met/1 g cow casein hydrolysate. The covalent nature of the amino acid incorporation was confirmed by SDS - polyacryl amide gel electrophoresis in the presence of urea. Electrophoretic patterns of the products indicate that transpeptidation plays an essential role in the EPM reaction. Antigenic character of the EPM- products was investigated in vitro by competitive indirect ELISA. Enzymatic peptide modification with methionine enrichment seems to be an efficient method for the reduction of the antigenic/potential allergenic character and for the improvement of the nutritive value of buffalo and cow milk caseins.