Monitoring of Oxidation Process of Human Milk Lipid Substitutes by Molecular Fluorescence Spectroscopy / 分析化学

The fatty acid contents in soybean oil, corn oil, coconut oil, sunflower seed oil and fish oil were detected by gas chromatography. According to the characteristics of fatty acids of raw oil and the relevant regulations of GB 10765-2010,the formula of 6 kinds of human milk lipid substitutes was designed by Matlab software and Excel linear programming. At the same time, the Schaal oven accelerated oxidation method was used to study the oxidation process of 6 formulations using synchronous fluorescence technique combined with traditional chemical reagents (oxidation index:peroxide value,value of fennel and total oxidation value). By statistical analysis of data, the statistical relationship between fluorescence intensity and oxidation index was explored. The results showed that the main fatty acids of coconut oil were lauric acid and myristic acid,and its saturated fatty acid content was the highest 93.75% ±0.06%;while all the other oils were mainly composed of palmitic acid,linoleic acid and other components,wherein the fish oil had the highest content of unsaturated fatty acid. With the increase of oxidation time,the fluorescence intensity decreased gradually and the oxidation index value increased continuously. The correlation analysis and regression analysis results showed that the change of oxidation index and the fluorescence intensity of 6 samples had negative correlation, and the fluorescence intensity and the peroxide value and total oxidation value was quadratic linear correlation, and anisidine value as a linear correlation had strong correlation.

Investigation of binding behaviour of procainamide hydrochloride with human serum albumin using synchronous, 3D fluorescence and circular dichroism / 药物分析学报

Interaction of procainamide hydrochloride (PAH) with human serum albumin (HSA) is of great significance in understanding the pharmacokinetic and pharmacodynamic mechanisms of the drug. Multi-spectroscopic techniques were used to investigate the binding mode of PAH to HSA and results revealed the presence of static type of quenching mechanism. The number of binding sites, binding constants and thermodynamic parameters were calculated. The results showed a spontaneous binding of PAH to HSA and hydrophobic interactions played a major role. In addition, the distance between PAH and the Trp–214 was estimated employing the F?rster's theory. Site marker competitive experiments indicated that the binding of PAH to HSA primarily took place in subdomain ⅡA (Sudlow's site I). The influence of interference of some common metal ions on the binding of PAH to HSA was studied. Synchronous fluorescence spectra (SFS), 3D fluorescence spectra and circular dichroism (CD) results indicated the conformational changes in the structure of HSA.

Study on the Interaction between Cefprozil and Bovine Serum Albumin by Spectrometry / 中国药房

OBJECTIVE:To study the interaction of cefprozil (CE) with bovine serum albumine (BSA). METHODS:Under the temperatures of 289,299 and 309 K,the interaction of CE with BSA for 50 min had been studied by fluorescence quenching, UV spectrometry and synchronous fluorescence spectroscopy. Quenching constant(KSV)and speed constant(Kq)were calculated by Stern-Volmer equation. Static quenching constant(KLB)was obtained by Lineweaver-Burk equation,and UV spectrogram was used to determine the type of quenching. Double logarithmic equation was used to calculate the binding constants (Kb) and the number of binding site(n). Thermodynamic equation was used to obtain ΔH,ΔS,ΔG. Hill's coefficients(nH)was obtained by Hill equa-tion. RESULTS:At three different temperatures,with CE concentration increasing,fluorescence intensity of BSA decreased regular-ly. The value of KSV,Kq,KLB,Kb and n and nH decreased with the temperature increasing. ΔH,ΔS and ΔG were lower than 0. The numbers of binding sites were approximately equal to 1 and nH<1. CONCLUSIONS:CE statically quench the fluorescence of BSA,and the binding of them have been found to certain extent. The process of binding is spontaneous exothermic process. The main binding forces include Hydrogen bonds and Van der Waals forces,and primary binding site for CE is located at sub-domain ⅡA of BSA. There was some negative cooperative effect. CE would not affect the conformation of BSA. The binding site of CE and BSA is near by tyrosine residue.

Multi-spectroscopic investigation of the binding interaction of fosfomycin with bovine serum albumin☆ / 药物分析学报

The interaction between fosfomycin (FOS) and bovine serum albumin (BSA) has been investigated effectively by multi-spectroscopic techniques under physiological pH 7.4. FOS quenched the intrinsic fluorescence of BSA via static quenching. The number of binding sites n and observed binding constant KA were measured by the fluorescence quenching method. The thermodynamic parameters △G0, △H0 and △S0 were calculated at different temperatures according to the van't Hoff equation. The site of binding of FOS in the protein was proposed to be Sudlow's site I based on displacement experiments using site markers viz. warfarin, ibuprofen and digitoxin. The distance r between the donor (BSA) and acceptor (FOS) molecules was obtained according to the F?rster theory. The effect of FOS on the conformation of BSA was analyzed using synchronous fluorescence spectra (SFS), circular dichroism (CD) and 3D fluorescence spectra. A molecular modeling study further confirmed the binding mode obtained by the experimental studies.

Spectroscopic study on interaction of quercitrin with human serum albumin / 中草药

Objective: To study the interaction of quercitrin with human serum albumin (HSA) and the influence of glucose. Methods: To investigate the interaction mechanism between quercitrin and HSA by spectroscopic method; to calculate the binding constants, binding sites, and binding distance according to double logarithmic plot and Föster's energy transfer theory, respectively; to explain the type of interaction force between quercitrin with HSA by thermodynamic parameters; to discuss the conformation change of HSA via synchronous fluorescence spectra. Results: The fluorescence quenching mechanism of quercitrin to HSA was static quenching; The binding constants and the number of binding sites decreased with the increasing of temperature and glucose; The distance between the donor and acceptor was less than 7 nm; The hydrophobic forces played a major role in stabilizing quercetrin and HSA complex; The binding reaction had changed the micro-environmention of tryptophan residues. Conclusion: Quercetrin could bind with HSA and change the conformation of HSA; The physiological concentration of glucose increases the binding constants and the number of binding sites of quercetrin with HSA.

Spectroscopic studies on the interaction of efonidipine with bovine serum albumin

Efonidipine hydrochloride is an antihypertensive and antianginal agent with fewer side effects and is better tolerated in the treatment of hypertension with renal impairment. Its interaction with bovine serum albumin (BSA) is of great use for the understanding of the pharmacokinetic and pharmacodynamic mechanisms of the drug. The binding of efonidipine to BSA was investigated by fluorescence spectroscopy and circular dichroism. BSA fluorescence was quenched by efonidipine, due to the fact that efonidipine quenched the fluorescence of tryptophan residues mainly by the collision mode. The thermodynamic parameters ÄH0 and ÄS0 were 68.04 kJ/mol and 319.42 J·mol-1·K-1, respectively, indicating that the hydrophobic interactions played a major role. The results of circular dichroism and synchronous fluorescence measurements showed that the binding of efonidipine to BSA led to a conformational change of BSA. The fraction of occupied sites (è) for the 8-anilino-1-naphthalein-sulfonic acid (ANS)-BSA system is 85 percent, whereas for the NZ-105-BSA system, it is 53 percent, which suggests that the interaction of ANS with BSA is stronger than that of NZ-105 with BSA. Binding studies in the presence of ANS indicated that efonidipine competed with ANS for hydrophobic sites of BSA. The effects of metal ions on the binding constant of the efonidipine-BSA complex were also investigated. The presence of metal ions Zn2+, Mg2+, Al3+, K+, and Ca2+ increased the binding constant of efonidipine_BSA complex, which may prolong the storage period of NZ-105 in blood plasma and enhance its maximum effects.

Research on the interaction of mechanism between aspirin and human serum albumin / 中国药理学通报

Aim To study the fluorescence spectroscopy of human serum albumin(HSA)and the interaction of aspirin and HSA.Methods The quenching mechanism of the fluorescence of human serum albumin by aspirin was studied with the fluorescence.The interaction dissociation constants KD of human serum albumin and aspirin were determined at different temperatures according to double reciprocal Lineweaver-Burk plot and the main binding force was discussed by thermodynamic equations.The effect of aspirin on human serum albumin was also studied by synchronous fluorescence spectrometry.Results The quenching mechanism of aspirin to human serum albumin was static quenching.The interaction dissociation constants KD at 37℃,25℃ was 1.44?10-3 and 1.96?10-3 mol?L-1 respectively.The thermodynamic parameters of the reaction was-19.73 kJ?mol-1(?H),-16.21 kJ?mol-1(?G),-11.77 kJ?mol-1(?S).Conclusions The main binding force between aspirin and HSA was Van der Waals interaction.Aspirin binding on the human serum albumin could change the serum protein conformation.

Conformational Changes of Hemoglobin Induced by Surfactants / 环境与健康杂志

Objective To study the effects of surfactants on conformation of hemoglobin and further to understand the potential impact of surfactants in environment on human health. Methods The changes of the conformation of hemoglobin induced by cation and anion surfactants were investigated with four methods, such as synchronous fluorescence spectra, UV, electrochemistry and atom force microscope. Results The changes of the conformation of hemoglobin induced by anion surfactant were obvious but were not by cation surfactant. Conclusion Sodium lauryl sulphate, an anion surfactant, may change the conformation of hemoglobin.