[Studied on the determination of protein by probe of zinc 5-aminosalicylate]

Zinc 5- aminosalylicylate (5-ASZ), a new creative medicine, can react with serum albumin to form a complex. Based on this, a new method for the determination of proteins by synchronous fluorescence spectra under simulated physiological conditions was established using 5 - ASZ as a fluorescence probe. The spectral characterization and intensity of synchronous fluorescence were related to the value of deltalambda, reaction medium and reaction temperature, and so on. On basis of these, eperimental results show that, under the optimum conditions, the synchronous fluorescence intensity of the system is in proportion to the concentration of protein in the range of 1.66-496.8 microg x mL(-1) for human serum albumin (HSA). The detection limit was 0.88 microg x mL(-1) (n = 11) for HSA. On basis of these it had been applied to the determination of proteins in human serum, urine and spit samples with satisfactory results, the recovery was within the range of 98.0%-103.8%. Results suggested that the method possessed easy of implementation, rapidity, high sensitivity, broad linear range, and better RSD and recovery, and so on, and the method was employed directly to determine the total proteins in samples, which results were satisfactory.

[Determination of the proteins in serum albumins by synchronous fluorescence technique with 3-(2-cyanoethyl) cytosine as a probe]

Under simulative biological conditions and upon the interactions between 3-(2-cyanoethyl) cytosine (CECT) and human serum albumin (HSA) or bovine serum albumin (BSA), the authors studied the characteristics of synchronous fluorescence spectra of CECT-protein system with CECT as a molecular spectral probe. The spectral characteristics and intensity of synchronous fluorescence were related to the value of deltalambda, reaction medium, reaction temperature and so on. On the basis of these, the new method for the determination of proteins in serum albumin was developed with CECT as a molecular spectral probe. Under the optimum experimental conditions, the synchronous fluorescence intensities of CECT-HSA and CECT-BSA systems were in good proportion to the concentrations of HSA and BSA in the ranges of 0-441.4 and 0-351.0 microg x mL(-1), respectively. The detection limits were 0.023 and 0.035 microg x mL(-1), respectively. Relative standard deviations located between 12% and 3.3%, and the addition standard recovery was 97.2%-100.4% for all elements. The results suggested that the method features easy of implementation, rapidity, high sensitivity, broad linear range, and better RSD and recovery etc., and was employed directly to determine the total proteins in serum albumin samples with satisfactory results.

Fluorescent investigation of the interactions between N-(p-chlorophenyl)-N′-(1-naphthyl) thiourea and serum albumin: Synchronous fluorescence determination of serum albumin

The interactions between N-(p-chlorophenyl)-N'-(1-naphthyl) thiourea and serum albumin were investigated by fluorescence spectroscopy and UV absorption spectrum under physiological conditions. The results of spectroscopic measurements suggested that N-(p-chlorophenyl)-N'-(1-naphthyl) thiourea should have a strong ability to quench the intrinsic fluorescence of both bovine serum albumin and human serum albumin through static quenching procedure, and the hydrophobic interaction was the predominant intermolecular force stabilizing the complex. Thermodynamic parameter enthalpy changes (DeltaH) and entropy changes (DeltaS) were calculated according to the Vant'Hoff equation. The binding distances between N-(p-chlorophenyl)-N'-(1-naphthyl) thiourea and the proteins were evaluated on the basis of the theory of Föster energy transfer. In addition, the effects of other ions on the binding constants of complexes were also discussed. Synchronous fluorescence technology was successfully applied to the determination of serum albumins added to the CPNT solution.

Interactions between 1-benzoyl-4-p-chlorophenyl thiosemicarbazide and serum albumin: investigation by fluorescence spectroscopy

The interactions between 1-benzoyl-4-p-chlorphenyl thiosemicarbazide (BCPT) and bovine serum albumin (BSA) or human serum albumin (HSA) have been studied by fluorescence spectroscopy. By the analysis of fluorescence spectrum and fluorescence intensity, it was showed that BCPT has a strong ability to quench the intrinsic fluorescence of both bovine serum albumin and human serum albumin through a static quenching procedure. The binding constants of BCPT with BSA or HSA were determined at different temperatures based on the fluorescence quenching results. The binding sites were obtained and the binding force were suggested to be mainly hydrophobic. The effect of common ions on the binding constants was also investigated. A new fluorescence spectroscopy assay of the proteins is presented. The linear range is 5.36-67.0 microg mL(-1) with recovery of 101.1% for BSA, and the linear range is 8.28-144.9 microg mL(-1) with recovery of 102.6% for HSA. Determination of the proteins in bovine serum or in human serum by this method gives results which are very close to those obtained by using Coomassie Brilliant Blue G-250 colorimetry. A practical method was proposed for the determination of BCPT in human serum samples.

Fluorescence spectroscopy studies on 5-aminosalicylic acid and zinc 5-aminosalylicylate interaction with human serum albumin

The interaction between 5-aminosalicylic acid (5-ASA) or zinc 5-aminosalylicylate (5-ASZ) and human serum albumin (HSA) was studied by fluorescence spectroscopic technique. The binding constants of 5-ASA or 5-ASZ with HSA were determined at different temperatures under the optimum conditions. The binding sites were obtained and the acting force were suggested to be mainly hydrophobic. The effect of common ions on the binding constants was also investigated. A fluorescence spectroscopy assay of the proteins is presented in the paper. The determination results of the proteins in human serum by this method are very close to those obtained using Coomassie Brilliant Blue G-250 colorimetry, with relative standard deviations of 0.8-2.9%. A practical method was proposed for the determination of 5-ASA or 5-ASZ in human serum samples.