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Biomedical subjects

S G Skuridin

Publications and source records attributed to S G Skuridin.

At least 19 recordsLinked to original sources
PubMed1996

A new approach for creating double-stranded DNA biosensors.

The principle of 'sandwich'-type biosensors based on liquid-crystalline dispersions formed from [DNA-polycation] complexes is outlined. These biosensors will find application in the determination of a range of compounds and physical factors that affect the ability of a given polycationic molecule to maintain intermolecular crosslinks between neighbouring DNA molecules. In the case of liquid-crystalline dispersions formed from [DNA-protamine] complexes, the lowest concentration of hydrolytic enzyme (trypsin) detectable was approximately 10-(14) M.

Animals↗
PubMed1995

The reduction of thymine residues in DNA by the combined action of UV light and hypophosphite.

UV irradiation (lambda = 254 nm) of thymine and uracil in aqueous solution containing salts of phosphinic acid (hypophosphites) results in the formation of the corresponding dihydropyrimidine derivatives. The peculiarities of this new photochemical reaction consist of a specificity towards 2,4-dioxophyrimidines, a high quantum yield and a neutral pH optimum. The quantum yield of photoconversion of thymine at pH 7.0 is equal to 1.9 x 10(-2) in 1 M NaH2PO2; it is diminished to 8.5 x 10(-3) in 0.1 M NaH2PO2. The same decrease in quantum yield with concentration is also found for uracil and uridine; quantum yields of their transformations in 0.1 M NaH2PO2 at pH 7.0 are 6.6 x 10(-2) and 1.5 x 10(-1) respectively. The mild conditions and high quantum yields characteristic of the photoinduced reaction above open up the possibility of obtaining DNA molecules which contain among pyrimidine photoproducts mainly dihydropyrimidine residues. A correlation between various types of thymine modifications in UV-irradiated double-stranded DNA (dimers and dihydrothymidine residues) and the amplitude of the intense negative band in the circular dichroism (CD) spectra specific for DNA liquid crystalline dispersions has been established. A possible application of this base-specific modification to the investigation of nucleic acids is considered.

Circular Dichroism↗
PubMed1994

Photochemical alterations in DNA revealed by DNA-based liquid crystals.

The preparations of chicken erythrocyte linear double-stranded DNA and superhelical plasmid pBR322 DNA were irradiated by continuous low-intensity UV radiation (I = 25-50 W/m2, lambda = 254 nm) as well as by high-intensity picosecond laser UV radiation (I = 10(11)-10(13) W/m2, lambda = 266 nm). The effect of DNA secondary structure alterations on the formation of liquid-crystalline dispersions from UV-irradiated DNA preparations was studied. It was shown that in the case of linear DNA, watching the disappearance of abnormal optical activity characteristic for cholesteric liquid crystal we managed to detect the presence of photochemical alterations in DNA irradiated by low-intensity UV radiation at an absorbed energy of more than 20 quanta per nucleotide. In the case of superhelical DNA using enzyme treatment of liquid-crystalline dispersions and monitoring the appearance of abnormal optical activity, we detected the presence of photochemical alterations in DNA molecules after low-intensity UV irradiation at an absorbed energy of less than 4 quanta per nucleotide. Under the latter approach using picosecond UV laser irradiation at three different light intensities we were able to distinguish the different mechanisms of fine alterations in DNA secondary structure at an absorbed energy value of about 3 quanta per nucleotide.

Animals↗
PubMed1990

Effect of platinum(II) chemotherapeutic agents on properties of DNA liquid crystals.

We have investigated the X-ray and optical properties (CD spectra and polarization microscopy) of liquid-crystalline phases and dispersions formed on pretreatment of low molecular weight DNA with the platinum(II) coordination complexes, cis-diammine-dichloroplatinum(II) (DDP), 2,2'-bipyridinedichloroplatinum(II) (1) and 2,2'-bipyridineethylenediammineplatinum(II) (2). It is demonstrated that the platination of DNA leads to the ordering of neighbouring molecules of DNA in liquid-crystalline phases being diminished. The intense bands observed in the CD spectra of liquid-crystalline dispersions prepared from DNA pretreated with 1 or 2 can be used to determine the orientation of the latter compounds with respect to the helical axis of the DNA and to detect distortions in the secondary structure of DNA. The possible causes of the appearance of the intense bands in the CD spectra of liquid-crystalline phases and alterations in the manner of packing of the molecules of DNA within them are discussed.

Animals↗
PubMed1988

[DNA liquid crystals as a possible system of testing the interactions between DNA and biologically active compounds of platinum (II) and various antibiotics].

DNA liquid crystals forming in water-salt solutions containing polyethylene glycol were used as a system for testing consequences of reactions of antitumor compounds belonging to two different groups with molecules of nucleic acids. It was found that with due account of the level of DNA molecule filling with daunorubicin it was possible to form two cholester phases characterized by the textures of "finger prints" and CD spectra with intensive bands of unlike signs, as well as the nematic phase characterized by the texture of the "black twisted fiber" system and the absence of the CD spectrum intensive band. Modification of the DNA molecules resulting from the reaction with cysdichlorodiamine platinum (II) led to formation of a new liquid crystalline phase with properties differing from those of the liquid crystalline phases of the cholester or nematic type.

Antibiotics, Antineoplastic↗
PubMedDate not supplied

[Some X-ray diffraction parameters of liquid-crystalline dispersions of nucleic acid-chitosan complexes ].

Liquid-crystalline dispersions of nucleic acid-chitosan complexes (NA-chitosan) possess optical and X-ray diffraction properties different from those of "classical" cholesterics. It is possible that positive charge distribution (distance between charges, chitosan conformation, etc.) in the polymeric chain of chitosan molecule combining with NA molecule is the factor that affects the spatial structure of resulting dispersions.

Chitin↗
PubMedDate not supplied

[Molecular construction (superstructures) with adjustable properties based on double-stranded nucleic acids].

Formation of molecular construction that consists of double-stranded molecules of nucleic acids (or synthetic polynucleotides) located at the distance 30-50 A in the spatial structure of particles of their cholesteric liquidcrystalline dispersion and crosslinked by polymeric chelate bridges is described. The resulting superstructure, which possesses peculiar physicochemical properties, could be used as integral biosensor whose properties depend on temperature, the presence of chemical or biologically active compounds of different nature, etc.

Antibiotics, Antineoplastic↗