Samuel Rosenkranz

Silver Sulfadiazine: Interaction with Isolated Deoxyribonucleic Acid

Silver sulfadiazine (AgSu) was found to interact with isolated deoxyribonucleic acid (DNA) to form nondissociable complexes. These complexes differ in physical and chemical properties from those that are established when silver nitrate is added to DNA. The reaction between AgSu and DNA is visualized as occurring in two stages: (i) a weak and reversible interaction (intercalation) between DNA and the sulfadiazine moiety and (ii) a tight binding involving the silver atom. In the first stage, sodium sulfadiazine competes with AgSu for the DNA.

Further observations on the photooxidation of DNA in the presence of riboflavin

Illumination of DNA in the presence of riboflavin results in an increase in buoyant density and a decrease in the temperature of the thermal helix-coil transition (Tm). The increase in buoyant density is maintained even after thermal denaturation, which indicates that it reflects a chemical alteration of a DNA base (presumably guanine). beta-Carotene, a quencher of singlet oxygen, inhibits the increase in buoyant density but it prevents only partially the decrease in Tm. This is taken as an indication that the photo-induced alteration of the DNA structure is due to more than one reaction. Illumination of DNA in the presence of methylene blue also causes an increase in buoyant density , but this increase is not retained upon thermal denaturation.

2-haloethanols: Mutagenicity and reactivity with DNA

Summary Iodo-, bromo- and chloroethanol are mutagenic for Salmonella typhimuriurn . The mutations induced are of the base-substitution type. These haloethanols also preferentially inhibit the growth of DNA polymerase-deficient Escherichia coli . The order of the reactivities of the substances in these systems is bromoethanol > iodoethanol > chloroethanol. These alcohols react with and modify isolated DNA.

Degradation of DNA by cysteine

Abstract Exposure of DNA solutions to cysteine resulted in degradation of the polydeoxynucleotide. This reaction was inhibited by Na2 EDTA and by sodium citrate. Methylcysteine, mercaptoethanol, serine, and homocysteine did not exhibit this degradative effect. Preincubation of cysteine resulted in a more rapid rate of degradation thus suggesting that a product formed during incubation was responsible for the observed effects.

Reaction between DNA and N-hydroxyurethan

Abstract Two types of reactions between DNA and N- hydroxyurethan were detected. The predominant reaction involves degradation of the DNA. This reaction is promoted by oxidizing agents but it is blocked under reductive conditions and by scavengers of free radicals. It appears that N- hydroxyurethan must first be converted to an active intermediate prior to acting on DNA. Evidence is presented that this intermediate may be ethoxycarbonylurethan. A second reaction of hydroxyurethan was detected. It involves modification of deoxycytidine. This modification is blocked by oxidizing as well as by reducing agents and by scavengers of free radicals. The modified product may arise through the intermediary of ethoxycarbonylurethan (an oxidation product of hydroxyurethan). A similar modification of the cytosine residue of DNA may occur when single-stranded DNA is exposed to hydroxyurethan.

A study on the absorption of nucleic acids by charcoal

Abstract Although charcoal has a high affinity for denatured and for degraded DNA, this property is not useful in separating such molecules from high molecular weight double-stranded (native) DNA.