Metal ions are crucial for nucleic acid folding. From the free energy landscapes, we investigate the detailed mechanism for ion-induced collapse for a paradigm system: loop-tethered short DNA helices. We find that Na+ and Mg2+ play distinctive roles in helix-helix assembly. High [Na+] (>0.3 M) causes a reduced helix-helix electrostatic repulsion and a subsequent disordered packing of helices. I...

A series of chimeric plasmids was constructed using colicinigenic factor E1 (ColE1) DNA as the replicon and DNA fragments carrying the galactose or tryptophan operons from E. coli. Restriction endonuclease EcoRI digests of ColE1 DNA and various DNAs containing the trp or gal operons were joined by T4 polynucleotide ligase [polynucleotide synthetase (ATP), poly(deoxyribonucleotide):poly(deoxyrib...

An instrument has been constructed that can automatically and selectively remove the terminal nucleotide residue from a ribonucleic acid. The instrument is designed to repeat the degradation cycle. This process involves two steps: (1) The base and sugar fragments are removed by the combined action of periodate and amine. (2) The phosphate residue, attached to the originally penultimate residue,...

Thermodynamic features related to preparation and use of self-assemblies formed between multilamellar and unilamellar zwitterionic liposomes and polynucleotides with various conformation and sizes are presented. The divalent metal cation or surfactant-induced adsorption, aggregation and adhesion between single- and double-stranded polyribonucleotides and phosphatidylcholine vesicles was followe...

Thermodynamic features related to preparation and use of self-assemblies formed between multilamellar and unilamellar zwitterionic liposomes and polynucleotides with various conformation and sizes are presented. The divalent metal cation or surfactant-induced adsorption, aggregation and adhesion between single- and double-stranded polyribonucleotides and phosphatidylcholine vesicles was followe...