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PubMed1983

Information transfer in biological systems. Part I: Calculation of the information content of some amino acids, lipids, and nucleic acid bases.

The Information Contents (IC) of some small molecules (amino acids, nucleic acid bases, lipids . . .) have been calculated by a newly developed method. A coordinate system, in which parallel, linear, saturated . . . -CnH2n- . . . chains in space serve the dimensions, has been postulated and its properties have been mathematically characterized. The system is suitable for the crude calculation and comparison of the IC-s of small molecules using conventional methods of information theory. A series of calculations has been presented to illustrate the use of the method. The importance of the IC calculations for understanding some biochemical processes (receptor-ligand bindings, enzymatic reactions) is discussed.

Amino Acids↗
PubMed2002

Effect of season and artificial diet on amino acids and nucleic acids in gonads of green sea urchin Strongylocentrotus droebachiensis.

The content of total and free amino acids (FAA) in green sea urchin (Strongylocentrotus droebachiensis) gonads varied with the season and feeding on an artificial diet. Glycine was the dominant amino acid in each season contributing 12.9-16.6% to the total amino acid (TAA) content, peaking in the spring. In the FAA profile, glycine accounted for 30.3-61.4% in different seasons. A grain-based artificial diet had noticeable effects on the total and FAA compositions of S. droebachiensis. Although, glycine was the dominant amino acid in the TAA profile during early harvesting, tyrosine in gonads became more dominant on week 9 of feeding. Furthermore, glycine was the dominant amino acid in the FAA pool after feeding the artificial diet. The total FAA content in the gonads increased significantly (P<0.05) from 20.6 on week 0 to 180.6 mg/g dry mass tissue on week 3. There were no significant (P<0.05) changes between week 6 and week 9. Deoxyribonucleic acid (DNA) content exceeded that of ribonucleic acid (RNA) in each season, while in cultured urchins, RNA content exceeded that of DNA only on week 6. The RNA/DNA ratio was significantly increased in the summer, whereas this ratio was increased up to week 6 followed by a decrease on week 9 in cultured counterparts.

Amino Acids↗
PubMed1977

Transport of amino acids and nucleic acid precursors in malarial parasites.

In vitro studies have shown that exogenously supplied amino acids are transferred into the malaria-infected cell, where they are incorporated into proteins. Most amino acids appear to enter the cell by facilitated or simple diffusion; however, the high distribution ratios seen in Plasmodium knowlesi-infected cells are difficult to explain on this basis. The changes (leakiness) observed in amino acid transport in P. lophurae infected cells are probably the result of ATP depletion in the host cell as well as the elaboration of plasmodial substances. Depletion of isoleucine, methionine, and cysteine from the medium strikingly depresses the in vitro growth of P. knowlesi. The degree of amino acid incorporation into the malaria-infected cell is not correlated with the amount of a particular amino acid in the host cell haemoglobin, the decline of that amino acid in the plasma of infected animals, or the ratio of free amino acids of the erythrocyte to those of the plasma. In erythrocyte-"free" P. lophurae, carrier-mediated transport is apparently limited to a small number of amino acids; all others seem to enter by simple diffusion.Malaria-infected erythrocytes transport exogenously supplied purines at substantially higher rates than uninfected red cells. The preferred purines are adenosine, hypoxanthine, and inosine. The only pyrimidine incorporated is orotic acid. Thymidine, cytidine, and uridine do not readily enter the red cell, and incorporation does not take place because the parasites lack the appropriate enzyme for conversion to nucleotides. Erythrocyte-"free" P. berghei and P. lophurae take up purines and orotic acid. It has been suggested that in vivo the preferred purines are hypoxanthine and inosine, and that the transport locus for erythrocytes is specific for 6-oxopurines. Similar results of purine incorporation are reported for the insect stages of P. cynomolgi and P. berghei, although transport studies have not been carried out.

Amino Acids↗
PubMed2005

Study on the resonance light-scattering spectrum of anionic dye xylenol orange-cetyltrimethylammonium-nucleic acids system and determination of nucleic acids at nanogram levels.

The interaction of xylenol orange (XO) and nucleic acids in the presence of cetyltrimethylammonium bromide (CTMAB) in aqueous solution has been studied by a resonance light-scattering (RLS) technique with a common spectrofluorometer. In hexamethylenetetramine (HMTA) buffer (pH7.30), XO and nucleic acids react with cetyltrimethylammonium bromide to form large particles of three-component complex, which results in strong enhanced RLS signals characterized by three peaks at 295.9, 335.5 and 542 nm, Mechanistic studies showed that the enhanced RLS stems from the aggregation of XO on DNA through the bridged and synergistic effect of CTMAB. With the enhanced RLS signals at the three wavelengths, the enhanced RLS intensity is proportional to the concentration of nucleic acids in an appropriate range. The lowest limit of determination was 5.31 ng ml(-1), three synthetic samples of yDNA were analyzed satisfactorily.

Cetrimonium↗
PubMed1978

Amino acid-directed nucleic acid synthesis. A possible mechanism in the origin of life.

The fact that proteins contain only alpha-amino acids and that protein structure is determined by 3' leads to 5' linked ribonucleotides is postulated to be the result of the copolymerization of these molecules in the prebiotic environment. Ribonucleotides therefore represent partial degradation products and proteins represent a side reaction developing from copolymerization. The basic structural unit of copolymerization is a nucleotide substituted with an amino acid at the 2' postion. Characteristics of modern amino and ribonucleic acid structure are all consistent with and necessary for this hypothesis. The characteristics and individual base assignemnts of the code also provide strong support for origin from the postulated copolymers. All characteristics of the code can be accounted for by this single hypothesis.

Amino Acids↗
PubMed2004

Evaluation of a new automated, standardized generic nucleic acid extraction method (total nucleic acid isolation kit) used in combination with cytomegalovirus DNA quantification by COBAS AMPLICOR CMV MONITOR.

The new generic Total Nucleic Acid Isolation kit improved the detection limit of a cytomegalovirus (CMV) PCR from 400 to 200 copies/ml. Sensitivity and specificity in 30 CMV-positive and 100 negative samples were 100%. Analytical performance was excellent. The kit provides a reliable, standardized, and time-saving tool for DNA extraction.

Automation↗
PubMed1979

Nucleic acid homology studies of viral nucleic acids in idiopathic Parkinson's disease.

Reassociation kinetics analyses with radioiodinated herpes simplex type 1 DNA and influenza A/NWS RNA were performed in the presence of tissue nucleic acids from defined loci of the brains of nine patients with idiopathic Parkinson's disease, one normal control brain, and the brains of uninfected mice or mice infected with either herpes simplex type 1 virus or influenza A/NWS virus. Herpes simplex type 1 DNA was detected by an increased reassociation rate in the herpes simplex type 1 virus-infected mouse brains. Influenza A/NWS RNA was detected by reassociation in the influenza A/NWS virus-infected mouse brains. Experimental limits for the detection of homologous nucleic acids are given for each separate experiment with human or mouse tissue. Within these detection limits, nucleic acids complementary to herpes simplex type 1 DNA or influenza A/NWS RNA were not detected in any of the brains of patients with idiopathic Parkinson's disease.

Brain↗