Biomaterial Database

The transitions between left- and right-handed forms of poly(dG-dC). 1981

V I Ivanov, and E E Minyat

The circular dichroism study of water/trifluoroethanol (TFE) solutions of poly(dG-dC) has revealed the following: The polynucleotide is present as a B form up to a TFE content of 60% (v/v) or less. Then, a cooperative transition into a left-handed Z form occurs. Within the region of 66-78% TFE, a continuous non-cooperative change is going on which can be attributed to an intrafamily transition within the family of Z forms. At last, in the interval of 80-84% TFE, a second cooperative transition, probably, Z - A is realized. Both transitions, Z - A and Z - B, show slow kinetics (10-60 min) while the direct transitions from the A to B form taking less than 10 sec. The length of cooperativity for the B - Z transition, Vo = 25 base pairs was estimated using spermine molecules. Spermine was found to induce the B to Z transition in the (dG-dC) sequences even in the absence of TFE which might be biologically interesting.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D009690	Nucleic Acid Conformation	The spatial arrangement of the atoms of a nucleic acid or polynucleotide that results in its characteristic 3-dimensional shape.	DNA Conformation,RNA Conformation,Conformation, DNA,Conformation, Nucleic Acid,Conformation, RNA,Conformations, DNA,Conformations, Nucleic Acid,Conformations, RNA,DNA Conformations,Nucleic Acid Conformations,RNA Conformations
D011089	Polydeoxyribonucleotides	A group of 13 or more deoxyribonucleotides in which the phosphate residues of each deoxyribonucleotide act as bridges in forming diester linkages between the deoxyribose moieties.	Polydeoxyribonucleotide
D002942	Circular Dichroism	A change from planar to elliptic polarization when an initially plane-polarized light wave traverses an optically active medium. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Circular Dichroism, Vibrational,Dichroism, Circular,Vibrational Circular Dichroism
D013056	Spectrophotometry, Ultraviolet	Determination of the spectra of ultraviolet absorption by specific molecules in gases or liquids, for example Cl2, SO2, NO2, CS2, ozone, mercury vapor, and various unsaturated compounds. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Ultraviolet Spectrophotometry
D013096	Spermine	A biogenic polyamine formed from spermidine. It is found in a wide variety of organisms and tissues and is an essential growth factor in some bacteria. It is found as a polycation at all pH values. Spermine is associated with nucleic acids, particularly in viruses, and is thought to stabilize the helical structure.