Separation of purine derivatives by polymer-bound nucleic acid bases

Separation of a variety of purine bases, which include 7-methyl derivatives, was studied by using polyethyleneimine-coated silicagel which bound hypoxanthine, cytosine or guanine moieties. The separation behavior seems to be related to the interaction of imidazole part of purine derivatives with the resins through hydrogen bonding.     

Reaction of nucleic acids bases and their derivatives with peroxodisulfate ion

Reaction with peroxodisulfate ion was investigated, that is, reaction of 1,3-dimethyluracil, 1,3-dimethylthymine, and caffeine with carbon radicals formed from decarboxylation of carboxylic acids, oxidation of the methyl group at 5-position of thymines, and halogenation of nucleic acids bases and their derivatives with alkali halides.     

Affinity chromatography of nucleosides and nucleic acid base derivatives with nucleic acid bases or nitrobenzeneboronic acid substituted silicas

Nucleic acid bases such as adenine and uracil, and nitrobenzeneboronic acid substituted silicas were prepared by the reaction of chloromethylbenzene substituted silica with adenine sodium salt and trimethylsilylated uracil, and nitration of benzeneboronic acid substituted silica, respectively. From the results of HPLC of nucleosides and N-ethyl derivatives of nucleic acid bases using modified silicas, hydrophobic base stacking interaction, selective hydrogen bonding interaction between purine and pyrimidine bases, and reversible cyclic boronate ester formation between diols of nucleosides with boronic acid were effective for the separation of nucleic acid related compounds. Moreover, association constants for hydrogen bonding formation of nucleic acid bases were estimated.     

Separation of platinated derivatives of nucleic acid bases on Sephadex G10

dGMP, dAMP, dCMP and dTMP were incubated with cis PDD in a nucleotide/Pt ratio 1:1 for 72 h. Following hydrolysis, Pt derivatives of the bases were separated on Sephadex G10 columns. dGMP, dAMP and dCMP reacted with cis PDD but only dGMP reacted completely. All the nucleotides mentioned above formed adducts with cis PDD with a metal to ligand ratio 1:1. Moreover an ML2 complex was isolated after the reaction of dGMP with cis PDD. These Pt-base(s) complexes were eluted from the columns in separate peaks. UV spectra of the complexes differed from the standard ones. In some peaks, eluted separately from the standards, no Pt was detected. The samples eluted in these peaks had UV spectra different from the standards. They may represent products of base degradation.     

The behavior and effect of isopoly (S-carboxymethyl-L-cysteine) derivatives of nucleic acid bases.

Isopoly(S-carboxymethyl-L-cysteine) derivatives of nucleic acid bases were prepared as antisense compounds. These compounds in vitro have been found to form stable complex with oligo-DNA or RNA. This paper deals with effect of antisense compounds in vivo. The target in this paper is the sequence of the PSD-95 protein linked with NMDA receptor. Excess passing of calcium ions through the loss of the signal pathway without PSD-95 proteins caused by antisense compound. The cells detailing with L-cysteine derivatives showed the lowest percentage of 19.1%. The data were compared with that of phosphotioate antisense compound.     

Alkylation of nucleic acid components by ethyleneimine derivatives. I. Alkylation of bases

In the course of investigating the reaction conditions of the nucleic acid components alcylation, the interaction of thioTEPA (N,N',N'-triethylenethiophosphoamide) with hydrochloric and perchloric acids was studied, perchloric acid increasing the alkylation products yield. HPLC and UV spectroscopy were used to isolate and identify products of nucleic bases alkylation by ethylenimine and its derivatives (thioTEPA and monoaziridinediethylphosphate). It is shown that under neutral conditions phosphoaminoethylation takes place, whereas under slightly acidic conditions products of aminoethylation are formed.     

Thermochemistry of aqueous solutions of alkylated nucleic acid bases. III. Enthalpies of hydration of uracil, thymine and their derivatives

Enthalpies of sublimation DeltaH(0)(subl) crystalline uracil, thymine and their methylated derivatives as well as of N,N-diethylthymine were determinated by the quartz-resonator method and mass spectrometry. Enthalpies of solution at infinite dilution DeltaH(0)(sol) in water of aBcylated compounds were obtained calorimetrically. Hence the calculated enthalpies of hydration: DeltaH(0)(hydrsubal) = DeltaH(0)(sol) - DeltaH(0)(subl), were corrected for energies of cavity formation in pure liquid water to yield enthalpies of interaction DeltaH(0)(sint) of the solutes with their hydration shells. For uracil DeltaH(0)(int) = -59.8 kJ mole(-1) was obtained in this way. This value decreased linearly on N-methyl substitution with a mean increment of about 6.5 kJ mole CH2(-1). After C(5) or C(6) ring substitution it increased by about 3 kJ. These results are discussed in connection with heat of dilution data and theoretical schemes of hydration.     

Out-of-plane vibration modes of nucleic acid bases

The out-of-plane vibration modes of uracil, cytosine and their deuterated and methylated derivatives such as 1,5-dimethyluracil (1-methylthymine), I-methylcytosine, 5-methylcytosine and 1,5-dimethylcytosine have been computed. The calculated wave-numbers have been compared to the published Raman peak and infrared band positions observed for solid or aqueous samples. The calculations have been carried out on a non-redundant set of symmetrical coordinates and a valence force field has been used. Some characteristic modes located between 750 and 800 cm^-1 found in the infrared spectra of 2-deoxycytidine, 2-deoxythymidine 5-monophosphate and polynucleotides containing cytosine and thymine bases can be interpreted from the calculated results on 1-methylthymine and 1-methylcytosine.     

Transport of nucleic acid bases against their concentration gradients through quaternized chitosan membrane

A water-insoluble anion exchange membrane was prepared by crosslinking with ethyleneglycol diglycidylether, a membrane made of quaternized chitosan and poly(vinyl alcohol). The transports of nucleic acid bases such as uracil, cytosine, adenine, and guanine were investigated as one side of the membrane in a diaphragm cell was acidic and the other basic. Uracil was transported against its concentration gradient from the basic side to the acidic side regardless of the pH on the basic side. Cytosine, adenine, and guanine were also transported against their concentration gradients, but the direction of their transport depended upon the pH on the basic side. In particular, the transport directions for adenine and guanine were switched during identical transport experiments. Mechanisms for the transport of these nucleic acid bases against their concentration gradients through the quaternized chitosan membrane are discussed.