Hypochromism accompanying purine-pyrimidine association interactions

Functional Monomers and Polymers CLXXVII.* Synthesis and Interaction Studies of Water Soluble Nucleic Acid Analogs: Polyethyleneimine Derivatives Containing Uracil and 5- Fluorouracil

Nucleic acid analogs were prepared by grafting uracil and 5-fluorouracil de rivatives containing a hydroxy group onto linear polyethyleneimine. The polymers contained about 90 unit% of the nucleic acid bases, and were freely soluble in water at neutral pH value. They were found to form polymer com plexes with polynucleotide by specific base-base interaction in aqueous solu tion.

Synthesis and Properties of Hyaluronic Acid Conjugated Nucleic Acid Analogs—1: Synthesis of Deacetylhyaluronan and Introduction of Nucleic Acid Bases

The conjugation of nucleic acid base with hyaluronan was achieved by using the activated ester of pentachlorophenyl trichloroacetate. The conditions of de-N-acetylation of sodium hyaluronic acid were studied. In low concentrations of NaOH, the degree of deacetylation was 26%, while in 7.4N NaOH, the degree of deacetylation was 76% and the viscosity was 1.12 dL/g. Thymine and 5-fluorouracil bases were quantitatively conjugated to deacetylhyaluronan in 65% and 51%, respectively. The interaction of thymine hyaluronan conjugate with the complementary base of polyadenylate showed a small hypochromicity.

Synthesis and Interaction Studies on Water Soluble Nucleic Acid Analogs: Poly(L-lysine) Derivatives Containing Thymine and Hypoxanthine*

Nucleic acid analogs were prepared by grafting nucleic acid base derivatives containing hydroxy groups onto poly(L-lysine). The polymers con tained about 70 unit% of the nucleic acid bases, and were easily soluble in water at neutral pH value. Conformational changes and polymer complexes with polynucleotides [Poly(A) and Poly(C)] were observed with specific base- base interactions in aqueous solution.

Triazole-linked analogue of deoxyribonucleic acid ((TL)DNA): design, synthesis, and double-strand formation with natural DNA

A new triazole-linked analogue of DNA ((TL)DNA) has been designed and synthesized using click chemistry. The chain elongation reaction using copper-catalyzed Huisgen cycloaddition was successful and gave the artificial oligonucleotide that formed a stable double strand with the complementary strand of natural DNA.

External reversible control of recognition behavior of alpha-peptide ribonucleic acid (alpha-PRNA) through anti-syn orientational switching of the nucleobase induced by borate esterification of the cis-2',3'-diol

A novel nucleic acid model using peptide ribonucleic acid (PRNA), which contains 5'-amino-5'-deoxypyrimidine ribonucleoside as a recognition site for nucleic acids, has been designed, synthesized and applied to the external reversible control of recognition behavior of the complementary polynucleotide through the orientational switching of the nucleobase induced by borate.

Effect of pisiferic acid and its derivatives on cytotoxicity macromolecular synthesis and DNA polymerase alpha of HeLa cells

1. Seventy-seven derivatives of pisiferic acid (2), an antimicrobial diterpenoid, were tested for cytotoxicity against HeLa cells and 9 derivatives were found to show cytotoxicity at less than 2 micrograms/ml dose (IC50). 2. Hydrophobicity was revealed to be an important factor for cytotoxicity of the derivatives. 3. Compound 2 inhibited predominantly DNA synthesis in HeLa cells as compared with RNA and protein synthesis. 4. No direct interaction between 2 and nucleic acid bases was indicated by a u.v. spectral method. 5. Several of the pisiferic acid species showed inhibitory action on HeLa DNA polymerase alpha, and the inhibitory activity was about 1/20 of aphidicolin.

Association by hydrogen bonding of mononucleotides in aqueous solution

Evidence for hydrogen bonding between 5'-ribonucleotides in water has been obtained from a 220-MHz proton magnetic resonance study of nitrogenous protons. The amino groups of GMP, AMP, and CMP exhibit proton resonance lines which are somewhat broadened by proton exchange with the solvent at 0 degrees ; their downfield Shifts in mixtures of mononucleotides provide the basis for the following order of base-pairing tendencies: GMP.CMP > AMP.UMP. Hydrogen bonding is also observed in other pairs of mononucleotides, notably GMP.UMP, AMP.CMP, and CMP.UMP, to a lesser extent in GMP.IMP, CMP.XMP, and possibly in CMP.IMP. In agreement with previous reports, hydrophobic interactions of mononucleotides have also been observed; base pairing occurs in addition to vertical stacking of these bases, their hydrogen bonding to water, or self-association. Only CMP shows clear evidence of self-association via hydrogen bonding in water; the evidence for GMP is less direct, and that for AMP is negative. This lack of observable self-association may occur as a result of competition from strong stacking interactions. Only CMP shows restricted rotation of the amino group at 0 degrees and neutral pH. As expected, higher temperatures increase the rate of rotation of the amino group for CMP, as well as accelerate the rate of proton exchange between water and the amino protons of mononucleotides.High-resolution proton magnetic resonance spectroscopy could prove to be a valuable tool in mapping out the specificities conferred by hydrogen bonding between biomolecules in aqueous solution.