Organic Small Molecule Probes

2-(8-hydroxyl quinoline-5-sulfoacid-7-azo)-1,8-dihydroxy-3,6-naphthalene di-sulfoacid, aristolochic A, monoammonium glycyrrhizinate were proposed as probes of protein. Puerarin was proposed as a probe of nucleic acids. Results showed that:1. The binding of 2-(8-hydroxyl quinoline-5-sulfoacid-7-azo) -1,8-dihydroxy -3,6-naphthalene disulfoacid (8Q5SAC) to bovine serum albumin (BSA) in acid solution was studied by using spectrophotometric method and equilibrium dialysis method, It is considered that the nonconvalent binding forces (mainly the electrostatic force) are the binding force between 8Q5SAC and BSA. The reaction mode was also discussed, the maximum binding number was determined to be 33-40; The binding constant was 6.1 + 105 L/mol at 298K. The absorption character of 8Q5SAC-BSA at various conditions (such as acidity, ionic strength and et.al.) was also studied. At pH3.34, the linear range of standard wave was 0.20-46.90 mg/L.2. The binding characteristics of aristolochic acid A with bovine serum albumin (BSA) have been studied by spectroscopy method and electrochemical method in aqueous solution. The formation constant KA and the thermodynamic functions (such as A G, AH and AS) for the reaction have all been measured; The effect of various metal ions and temperatures on the formation constant of aristolochic acid A with BSA was also studied; The effect of aristolochic acid A on the conformation of BSA has also been analyzed using synchronous fluorescence spectroscopy; The binding distance between aristolochic acid A and BSA and the transfer efficiency have been obtained based on the mechanism of Forster energy transfer.3. The fluorescence quenching mechanism of bovine serum albumin (BSA) by monoammonium glycyrrhizinate (MAG) has been studied. It is proved that static quenching exits between MAG-BSA super-molecular complex. The formation constant KA and the thermodynamic functions (such as A G, AH and AS) for the reaction have all been obtained. According to the thermodynamic parameters, the main sort of binding force was electrostatic force. The effect of various metal ions and temperatures on the formation constant of MAG with BSA was also studied; Thebinding distance between MAG and BSA and the transfer efficiency have been obtained based on the mechanism of Forster energy transfer; The effect of MAG on the conformation of BSA has also been analyzed using synchronous fluorescence spectroscopy.4. A novel fluoremetric method has been developed for rapid determination of DNA or RNA with puerarin as a fluorescence probe, based on the fluorescence quenching of puerarin in the presence of DNA or RNA. The maximum excitation and emission wavelengths are at 266 nm and 460 nm, respectively. Under optimal conditions, the calibration graphs are linear over the range of 2.9-76.0g/mL for fish sperm DNA (FS DNA) , 3.6-68.0g/mL for calf thymus DNA (CT DNA) ,1.1 -36.0g/mL for yeast RNA (YRNA) and 2.9-36.0g/mL for denatured DNA (Da DNA).The corresponding detect limits are 2.9g/mL for FS DNA, 3.6g/mL for CT DNA, 1.1g/mL for YRNA and 2.9g/mL for Da DNA. The relative standard deviation of five replicate measurements is 1.5% for 20g/mL FS DNA. The mechanism for the binding of puerarin to DNA is also studied.