Microcalorimetric and spectroscopic investigation of the antibacterial properties of cationic ytterbium(III)-porphyrin complexes lacking charged peripheral groups.

The antibacterial activities towards Escherichia coli of two cationic Yb(III)-monoporphyrin complexes, [Yb(III)(TMP)(H2O)3]Cl (1) and [Yb(III)(TTP)(H2O)3]Cl (2), were investigated at the cellular and sub-cellular levels. The biological effects of the complexes on the growth of E. coli were evaluated by microcalorimetry and by analysis of the resulting metabolic thermogenic curves, from which IC50 values and metabolic parameters such as growth rate and generation time were derived.

Antibacterial effects of a monoporphyrinato ytterbium(III) complex and its free components on Staphylococcus aureus as determined by stop-flow microcalorimetry.

The antibacterial effect of Yb3+, the free porphyrin base 5,10,15,20-tetrakis(4-methoxyphenyl)porphyrin (H2TMP; 1), and the corresponding Yb3+ porphyrinato complex [Yb(III)(TMP)(H2O)3]+ Cl- (Yb(TMP); 2) towards Staphylococcus aureus was investigated by stop-flow microcalorimetry. By analyzing the obtained metabolic thermogenic curves, crucial parameters such as rate constant of bacterial growth (k), half inhibitory concentration (IC50), and generation time (t(G)) were determined. The antibacterial activities of the three compounds tested was 2>1>Yb3+, with an IC50 value of 273 mg/l for complex 2.

[Thermochemical studies on the binding reaction of perseleno diphenyl 2,2'-diformic acid with bovine serum albumin].

The binding of newly compounded perseleno diphenyl 2,2'-diformic acid to bovine serum albumin(BSA) was studied at different temperatures using fluorescence spectrum and UV spectrum. The fluorescence quenching data was analyzed according to Stern-Volmer equation and Lineweaver-Burk double-reciprocal equation. It was showed that this quenching complies better with the charactristic of static fluorescence quenching.

Interaction of colchicine with human serum albumin investigated by spectroscopic methods.

We investigated the interaction between colchicine and human serum albumin (HSA) by fluorescence and UV-vis absorption spectroscopy. In the mechanism discussion, it was proved that the fluorescence quenching of HSA by colchicine is a result of the formation of colchicines-HSA complex; van der Waals interactions and hydrogen bonds play a major role in stabilizing the complex. The modified Stern-Volmer quenching constant K(a) and corresponding thermodynamic parameters deltaH, deltaG, deltaS at different temperatures were calculated.

Interaction of cromolyn sodium with human serum albumin: a fluorescence quenching study.

The interaction between cromolyn sodium (CS) and human serum albumin (HSA) was investigated using tryptophan fluorescence quenching. In the discussion of the mechanism, it was proved that the fluorescence quenching of HSA by CS is a result of the formation of a CS-HSA complex. Quenching constants were determined using the Sterns-Volmer equation to provide a measure of the binding affinity between CS and HSA.

Some properties of the interaction between 2,2'-diselenadibenzoic acid and serum albumins.

The binding of 2,2'-diselenadibenzoic acid to bovine serum albumin (BSA) and human serum albumin (HSA) was studied by using fluorescence spectroscopy. The measurement was performed in Tris-HCl buffer aqueous medium at pH = 7.40.

Fluorometric investigation of the interaction of bovine serum albumin with surfactants and 6-mercaptopurine.

Fluorescence quenching in solutions of bovine serum albumin has been investigated in the presence of 6-mercaptopurine and ionic surfactants. Spectroscopic analysis of the emission quenching at different temperatures revealed that the quenching mechanism of bovine serum albumin by 6-mercaptopurine was dynamic quenching mechanism. The Stern-Volmer quenching model has been successfully applied, and the activation energy of the interaction between 6-mercaptopurine and bovine serum albumin as much as 4.

Fluorometric investigation of the interaction between methylene blue and human serum albumin.

The interaction between methylene blue (MB) and human serum albumin (HSA) was investigated by fluorescence spectroscopy and UV-vis absorbance spectroscopy. In the mechanism discussion, it was proved that the fluorescence quenching of HSA by MB is a result of the formation of MB-HSA complex and electrostatic interactions play a major role in stabilizing the complex. The Stern-Volmer quenching constant K(SV) and corresponding thermodynamic parameters DeltaH, DeltaG and DeltaS were calculated.

Study of the interaction between monoammonium glycyrrhizinate and bovine serum albumin.

The interaction between monoammonium glycyrrhizinate (MAG) and bovine serum albumin (BSA) were studied by fluorescence and absorption spectroscopy. The quenching mechanism of fluorescence of bovine serum albumin by monoammonium glycyrrhizinate was discussed. The binding sites number n and apparent binding constant K were measured by fluorescence quenching method.

Absorption and fluorescence study of the interaction between (2-hydroxy-benzimido)ethyl-n-hexylselenide and bovine serum albumin.

The binding of Schiff base selenide, (2-hydroxy-benzimido)ethyl-n-hexylselenide, to bovine serum albumin (BSA) was studied using fluorescence spectroscopy. The measurement was performed in Tris-HCl buffer aqueous medium at pH 7.4.

[Study on thermodynamics of binding reaction of dipyridamole with bovine serum albumin].

The binding feature of dipyridamole with bovine serum albumin (BSA) was studied using fluorescence spectroscopy. It was shown that this compound has a powerful ability to quench the BSA fluorescence via a nonradiative energy transfer mechanism. The fluorescence quenching data were analyzed according to stern-volmer equation and double-reciprocal equation, and the binding constant and the thermodynamic parameters were obtained.

Microcalorimetric studies of the action of Na2SeO3 on the growth of Halobacterium halobium R1.

The effect of Na2SeO3 on the growth of Halobacterium halobium R1 was investigated by means of microcalorimetry at 37 degrees C. The biological response to toxicants is observed as the inhibition of the rate constant of growth of living cells. A low concentration of Na2SeO3 stimulated the growth of H.

Thermodynamics and kinetics of the cleavage of DNA catalyzed by bleomycin A5.

Microcalorimetry and UV-vis spectroscopy were used to conduct thermodynamic and kinetic investigations of the scission of calf thymus DNA catalyzed by bleomycin A5 (BLM-A5) in the presence of ferrous ion and oxygen. The molar reaction enthalpy for the cleavage, the Michaelis-Menten constant for calf thymus DNA and the turnover number of BLM-A5 were calculated by a novel thermokinetic method for an enzyme-catalyzed reaction to be -577 +/- 19 kJ.mol-1, 20.

Thermodynamics of binding of cadmium to bovine serum albumin.

The binding isotherm of Cd2+ ion to bovine serum albumin (BSA) has been investigated by microcalorimetry at 310.15 K and pH 7.0.