[The effect of structure of benzimidazoles on the character of forming intramolecular cross-links in DNA and chromatin].

An investigation of a number of benzimidazole class preparations, being distinguished by a position of aminomethyl substitutes, has been carried out. It has been shown, that the non-substituted preparation BIO-10 does not form UV-cross-links in DNA and chromatine; BIO-40, having one substitute in the position 2, causes the formation of inter-molecular cross-links DNA-DNA. The preparation BIO-50, having 2 aminomethyl groups in the imidazole nucleus positions 2 and 6, forms cross-links DNA-DNA and DNA-protein in chromatine.

[The action of benzimidazole derivative preparations on the formation of DNA-protein cross-links in the UV irradiation of chromatin].

Effect of benzimidazole-derivatives on the DNA-protein binding formation was studied after UV-radiation of chromatin. These derivatives were shown to protect chromatin from UV-induced DNA-protein binding formation. Structural analog contained two aminomethyl residuals sensibilized additional binding formation in chromatin.

[UV-induced formation of DNA-protein cross-links in chromatin in the presence of chemical agents].

Hindered phenols, quinones, and SH-compounds have been studied as possible protectors and sensitizers of DNA-protein cross-linking in chromatin. Efficacy of cross-linking was estimated by the quantity of protein linked to DNA after UV irradiation at 254 um in the presence of chemical agents. Phenols and quinones exert protective influence on cross-linking whereas DNA-protein cross-links are sensibilized by cysteine hydrochloride.

Complex formation of spin-labeled 9-aminoacridine with DNA and polynucleotides.

Complex formation between spin-labeled 9-aminoacridine and DNA or polynucleotides has been studied by differential spectrophotometry and ESR. The differential spectra of the strong type 9-aminoacridine-DNA complex showed characteristic absorption bands at 270 and 290 nm, and the intensity ratio of these bands varied according to the degree of DNA denaturation. The ESR spectra of this complex were characterized by slow rotation of the radical; as the macromolecule became increasingly denatured and in the polynucleotide complex, a rapid signal appeared in the ESR spectrum.

[Structural transitions in DNA, isolated from normal and neoplastic cells].

A decrease of temperature transition in spin-labeled DNA isolated from leucose cells compared with normal cells is found. It is shown by kinetic formaldehyde method that it may be the result of many defects in the secondary structure of macromolecule in DNA1. The spin label method is shown to be used for the analysis of DNA macromolecule damaged with small irradiation doses.