Presence Of Crystal Violet Research Articles

Evidence for free radical formation during horseradish peroxidase-catalyzed N-demethylation of crystal violet

Crystal violet (gentian violet) can undergo an oxidative metabolism, catalyzed by horseradish peroxidase, resulting in formaldehyde formation. The N-demethylation reaction was strongly inhibited by reduced glutathione. Evidence for the formation of a crystal violet radical during the horseradish peroxidase catalyzed reaction was the detection of thiyl and ascorbate radicals from glutathione and ascorbate, respectively. The concentration of radicals from both compounds was significantly increased in the presence of crystal violet. Oxygen uptake was stimulated when glutathione was present in the system and this oxygen uptake was dependent on the dye and enzyme concentration. Oxygen uptake did not occur when ascorbate, instead of glutathione, was present in the system. However, when glutathione was present, ascorbate totally inhibited the glutathione-stimulated oxygen uptake in the crystal violet/horseradish peroxidase/hydrogen peroxide system. Although a weak ESR spectrum from a crystal violet-derived free radical was detected when the dye reacted with H 2O 2 and horseradish peroxidase, using the fast flow technique, this spectrum could not be interpreted.

An in situ scanning tunnelling microscopy study of bulk copper deposition and the influence of an organic additive

In situ scanning tunnelling microscopy (STM) was used to study the electrodeposition of copper onto Au(111) and Au(100) electrodes from sulphuric and perchloric acid electrolytes. We also followed copper deposition in the presence of crystal violet, which has properties typical of additives used in metal plating baths. For both crystallographic orientations, and also with or without the additive, the very initial stages of copper electrocrystallization occurred predominantly at surface defects, such as step edges of the substrate surface. In the absence of additive the copper crystallites grew in three dimensions and the number of growth centres remained relatively constant, implying an instantaneous nucleation mechanism. However, the presence of small quantities of crystal violet in the electrolyte solution markedly influenced the growth of the copper crystallites, on both Au(111) and Au(100) substrates. Instead of growing in three dimensions they spread essentially parallel to the surface, to produce copper films which were much smoother on the microscopic scale.

Study of the initial stages of copper deposition by in situ scanning tunnelling microscopy

The initial stages of copper deposition on gold single-crystal electrodes, comprising the formation of a Cu monolayer at underpotentials as well as nucleation and growth of small Cu clusters at overpotentials, has been studied in various electrolytes by in situ scanning tunnelling microscopy (STM). Individual atoms of the bare gold surface and of the Cu adlayer in the underpotential deposition (UPD) range could be clearly resolved. The nucleation-and-growth behaviour of Cu in the absence and presence of crystal violet has been investigated. In both cases nucleation starts preferentially at surface imperfections such as step edges with a high density of kinks, but the organic additive has a marked influence on the growth behaviour, favouring a quasi-two-dimensional spreading across the surface. The development of the shape of a Cu cluster with time during the deposition process has also been monitored. Finally, possible influences of the tip on the growth behaviour are discussed.

Electrical Resistance of Black Lipid Membranes in the Presence of Crystal Violet

AbstractThe resistance of black spherical lipid membranes decreases linearly with increasing concentration of crystal violet (CV). This decrease is not influenced by the variation of the electrolyte concentration or of pH in the aqueous membrane bathing solutions. When the CV‐concentrations on the two sides of the membrane are different, an electric potential characteristic of a CV‐selective membrane is created.

Bacterial Cell Division Regulation: Physiological Effects of Crystal Violet on Escherichia coli lon + and lon − Strains

The Escherichia coli lon(-) mutants apparently are defective in the ability to recommence cell division after temporary periods of deoxyribonucleic acid (DNA) synthesis inhibition. They are also more susceptible to cell division inhibition by the basic dye, crystal violet (CV), than are lon(+) strains. In enriched broth, the lon(+) strain continued to grow and divide in the presence of CV, but lon(-) cell division was inhibited and filamentous growth resulted. In a supplemented minimal medium containing CV, lon(-) cell division was only temporarily inhibited. There was no detectable specific effect on DNA synthesis, although CV slowed the rate of mass increase in both media. Trichloroacetic acid-insoluble lipid synthesis was preferentially inhibited in both lon(+) and lon(-) strains. In CV-containing enriched broth, diaminopimelic acid incorporation into trichloroacetic acid-insoluble compounds occurred at a rate greater than the rate of mass increase in both lon(+) and lon(-) strains. In a CV-containing supplemented minimal medium, diaminopimelic acid was incorporated to a greater extent by lon(-) cells than by lon(+) cells.

The effect of bacteriostatic agents on the electrokinetic properties of Aerobacter aerogenes: II. Crystal violet

1. 1. Crystal violet acting on resting cells of Aerobacter aerogenes caused a decrease of electrophoretic mobility with increasing concentration, very high concentrations causing flocculation. 2. 2. Individual cells showed a non-uniform response to the action of the drug at high concentrations. 3. 3. During the first subculture of untrained cells in crystal violet medium, three different types of electrokinetic behaviour were apparent. The type of behaviour exhibited depended on the age of the parent inoculum. 4. 4. It has been established that the change of electrokinetic properties occurs only during cell division in the presence of crystal violet, never in its absence. 5. 5. Each of the three types of behaviour was found to be transmitted without change on subsequent subculture in the presence of low drug concentrations. Growth in higher concentrations was without effect on two of these types of behaviour, the intermediate type B however, tended towards that of type C. 6. 6. Growth of the trained organisms in the absence of the drug caused a change in the electrophoretic mobility distribution for types B and C behaviour towards that of type A. Nutrient broth was more effective in bringing about this change than synthetic medium.