Liquid crystalline microphases of DNA molecules complexed with compounds of platinum(II)

Abstract

The formation of liquid crystalline microphases (0.3 M NaC104, and 120 and 170 mg PEG/ml) from lowMr DNA (salmon sperm) complexed with cis and trans dichlorodiamine-platinum(I1) was investigated. It was shown that the amplitude of the negative band in the CD spectrum, characteristic of a liquid crystalline microphase of DNA, decreased upon complexing with platinum compounds. It was estimated that the influence of cis Pt(I1) on the optical properties of liquid crystalline microphase of DNA molecules strongly differed from the effect of trans Pt(I1); the phenomenon did not depend on [PEG]. The reasons of the decrease of the negative band in the CD spectra of the DNA liquid crystalline microphases are discussed.

The EB-DNA Liquid Crystalline Complex with High Concentration of Mg2+

“…[12][13][14] In the DNA cholesteric phase, the local orientation direction of the DNA chains is perpendicular to the cholesteric axis, which regularly rotates with a constant twist. This molecular arrangement of the DNA chains is influenced by many factors, such as ionic strength, temperature, the length of DNA chains and small molecule binding with the DNA chains, [15][16][17] etc.…”

DNA conformation and repair of polymeric natural DNA damaged by antitumor azolato-bridged dinuclear PtII complex

“…Liquid crystalline dispersions of double-helical DNA (pSP73KB plasmid linearized by NdeI) modified by the platinum complexes were formed by mixing DNA and PEG solutions as described earlier [27,28]. Briefly, 1 mL of non-modified DNA or DNA modified by the platinum complex dissolved in NaClO 4 (0.01 M) at the concentration of 0.06 mg mL − 1 was mixed vigorously with 3 mL PEG (200 mg mL − 1 ) [also dissolved in NaClO 4 (0.3 M] for 1 hr.…”

“…7) [41][42][43][44]. The decrease in the amplitude of this band in the CD spectra of liquid crystalline dispersions of DNA modified by antitumor platinum complexes is associated with the disappearance of the helical twist of the liquid crystalline microphase due to alterations of DNA secondary structure, such as disturbances in the stacking interactions of bases [27,41,45]. Interestingly, clinically ineffective platinum complex, such as monofunctional [PtCl(dien)] + whose adducts distort DNA conformation markedly less than the adducts of bifunctional cisplatin, affected the CD spectra of liquid crystalline dispersions of DNA only negligibly (see also Fig.…”

“…7). Thus, the CD spectra of liquid crystalline microphases of DNA modified by platinum compounds are very sensitive to the extent of conformational alterations the platinum compounds induce in DNA [27].…”