Changying Guo

Fluorescence enhancement effect for the determination of proteins with morin–Al3+–cetyltrimethylammonium bromide

It is found that the fluorescence intensity of morin-Al(3+) complex can be greatly enhanced by proteins in the presence of cetyltrimethylammonium bromide (CTAB). It is considered that protein and CTAB provide a hydrophobic environment with low polarity and large viscosity, resulting in the fluorescence enhancement of morin-Al(3+) complex. The experiments indicate that under optimum conditions, the enhanced intensity of fluorescence is in proportion to the concentration of proteins (such as bovine serum albumin (BSA), human serum albumin (HSA) and egg albumin (EA)) in the wide range, and their detection limits (S/N=3) are 2.6 x 10(-9), 1.4 x 10(-8) and 1.6 x 10(-8) g ml(-1), respectively. This method has satisfactorily been used for the determination of protein in actual sample. In comparison with most of fluorimetric methods reported, this method is quick and simple, and has high sensitivity, wide linear range and good stability.

The Sensitive Determination of Nucleic Acids Using Fluorescence Enhancement of Eu3+-BenzoylacetoneCetyltrimethylammonium Bromide-Nucleic Acid System

A new quantitative method for micro amounts of nucleic acids in aqueous solution is proposed using Eu3+-benzoylacetone (BA) complex as fluorescent probe in the presence of cetyltrimethyl-ammonium bromide (CTMAB). Under the optimum condition, the ratio of the fluorescence intensities with and without nucleic acids is proportional to the concentration of nucleic acid in the range of 1.0 × 10-9 to 5.0 × 10-6 g/mL for herring sperm DNA (hsDNA), 3.0 × 10-9 to 1.0 × 10-6 g/mL for calf thymus DNA(ctDNA) and 8.0 × 10-9 to 1.0 × 10-6 g/mL for yeast RNA (yRNA), and their detection limits are 0.33, 0.21 and 0.99 ng/mL, respectively. Actual sample (DNA of Arabidopsis thaliana) was determined satisfactorily. In addition, the interaction mechanism is also investigated.

Novel biomarkers of protein oxidation sites and degrees using horse cytochrome c as the target by mass spectrometry.

Biomarkers held both incredible application and significant challenge in probing the oxidation mechanisms of proteins under oxidative stress. Here, mass spectrometry (MS) coupled with liquid chromatography (LC) was applied to establish a new pipeline to probe the oxidation sites and degrees of horse cytochrome c (HCC) with its oxidative products serving as the biomarkers. Samples of native and UV/H(2)O(2) oxidized HCCs were digested by trypsin and subjected to biomarker discovery using LC/MS and tandem mass spectrometry (MS/MS). Experiment results proved that the main oxidation sites were located at Cys(14), Cys(17), Met(65) and Met(80) residues in peptides C(14)AQC(heme)HTVEK(22), C(14)AQCHTVEK(22), E(60)ETLMEYLENPKK(73), M(80)IFAGIK(86) and M(80)IFAGIKK(87). Quantitative analysis on the oxidized peptides showed the oxidation degrees of target sites had positive correlations with extended oxidation dose and controlled by residues types and their accessibility to solvent molecules. Being able to provide plentiful information for the oxidation sites and oxidation degrees, the identified oxidized products were feasibility biomarkers for HCC oxidation, compared with the conventional protein carbonyl assay.

Resonance light-scattering enhancement effect of the protein-Y3+-TTA-SLS system and its analytical application.

In this paper, a sensitive resonance light scattering (RLS) method for the determination of protein is reported. In the Tris-HCl (pH 7.50) buffer, protein enhanced the RLS intensity of the Y(3+)-2-thenoyltrifluoroacetone (TTA)-sodium dodecyl sulphate (SLS) system. The enhanced RLS intensities were in proportion to the concentrations of proteins in the range 8.0 x 10(-9)-1.0 x 10(-5) g/mL for BSA, 1.0 x 10(-8)-1.0 x 10(-5) g/mL for HSA and 1.0 x 10(-8)-1.0 x 10(-6 )g/mL for EA, and their detection limits were 5.0, 5.4 and 6.7 ng/mL, respectively. Actual samples were satisfactorily determined. The interaction mechanism was also studied.

Study on a fluorometric method for the determination of protein in serum using quercetin-lanthanum (III)-sodium dodecyl benzene sulfonate-protein system

Abstract It was found that the fluorescence intensity of lanthanum (III) (La3+)‐quercetin (Qu) complex is greatly enhanced by proteins in the presence of sodium dodecyl benzene sulfonate (SDBS). Based on this finding, a new fluorimetric method for the determination of proteins was developed. Under optimum conditions, the enhanced intensity of fluorescence is in proportion to the concentration of proteins in the range of 2.5×10−8 to 1.0×10−5 g/mL for bovine serum albumin (BSA), 5.0×10−8 to 1.5×10−5 g/mL for human serum albumin (HSA), and 1.0×10−7 to 1.5×10−5 g/mL for egg albumin (EA). Their detection limits (S/N=3) are 5.0×10−9 g/mL, 7.0×10−9 g/mL, and 2.1×10−8 g/mL, respectively. The interaction mechanism was also studied.