| Nucleic acids(nucleoside)and proteins are the material base of all life.They relate to heredity,tumor,the effect of virus,and so on.So,it is very important for researchers to expound the secrets of life,to develop new functionalized medicine to treate many difficult diseases.What we should do is to further study the interaction mechanism between biomolecules and organic molecules(or biomolecules),to develop rapid and convince assay for biomolecules.This project is the forward position and hot point in biochemical and biophysical researches.This thesis studies the interaction mechanism between biomolecules and organic molecules(or biomolecules)using the techniques including fluorescence,absorption, RLS,CD and TEM.Some rapid,accurate assays with high sensitivity and selectivity are developed for nucleic acid and nucleoside.The main conclusions are listed as below:1.In the first section,we summarize recent developments of fluorescence probe for both nucleic acids and nucleoside,and comment on the experimental techniques to investigate the interaction between biomacromolecules and small molecules.142 references are cited here.2.In the second section,it is found that KI within a certain range of concentration can enhance the fluorescence intensity of morin-fsDNA system.Based on this phenomenon,a new and selective method for the determination of fsDNA is developed.Under the optimum conditions,the enhanced intensity of fluorescence is in proportion to the concentration of nucleic acids in the range of 8.0×10-9-2.0×10-5g mL-1for hsDNA and 5.0×10-9-1.0×10-5g mL-1for smDNA.Their detection limits are 4.5ng mL-1and 3.5ng mL-1,respectively.The interaction mechanism of KI-morinhsDNA system is studied.It is considered that there is the groove binding mode between KI-morin and DNA;the fluorescence enhancement effect induced by KI is attributed to the formation of the more favorable structure for the luminescence.3.In the third section,it is found that guanine can enhance the fluorescence of morin.Based on this,a new method for the determination of guanine is proposed.In NaAc-HAc buffer,the fluorescence intensity of morin system can be greatly enhanced by guanine and the enhanced intensity is in proportion to the concentration of guanine in the range 2.0×10-8-8.0×10-5mol L-1,its detection limits is 7.0×10-9mol L-1. Interference test shows that the other three bases in nucleic acids have little effects on the determination of guanine.And the mechanism study indicates that the fluorescence enhancement of morin is considered to originate from the formation of intermolecular multi-hydrogen bonds between guanine and morin,which can increase the co-planar effect and the structural rigidity of morin and reduce its energy consumption originated from molecular movement.Therefore,the fluorescence intensity and lifetime of morin can been enhanced.4.In the fourth section,we study the interaction mechanism of Epinephrine-NaOH-Actone-DAN-β-CDx system using the techniques including fluorescence, absorption,and CD.The constant and stoichiometric ratios in the system are calculated based on the "double reciprocal method".Results show that in the presence of acetone,the system forms 1:1 inclusion complex,the inclusion constant is 206L.mol-1;whereas in the absence of acetone,it forms 1:1 inclusion complex in low concentration ofβ-CDx,the inclusion constant is 68 L mol-1,then forms 2:1 inclusion complex with the increase ofβ-CDx concentration,the inclusion constant K2 is 1270 L mol-1.The CD spectra indicate that theβ-CDx include the guest with axial type in epinephrine-NaOH-DAN-β-CDx system.A large cooperative effect ofβ-CDx and low acetone concentration together produces a much larger enhancement.The addition of acetone makes the indole ring group of fluorescent condensate expose outside of the cavity ofβ-CDx,resulting in the formation of 1:1(or 2:2)inclusion complex because of stereo-hindrance effect.5.In the fifth section,it is found that BSA nanoparticles synthesized by a desolvation technique can emit the fluorescence peak at 430nm,which is considered to be the fluorescence peak of BSA aggregate;its intensity is greatly enhanced by nucleic acid in the presence of CTMAB.Based on this,a new method for the determination of nucleic acid is proposed.The interaction mechanism of this system is studied.It is considered that the nucleic acid acts as the template in the system,the positive charged CTMAB will assemble on the nucleic acid to form.positive charged pre-micelle.Hence to promote the assembly of negative charged BSA anoparticles on the pre-micelle and form large aggregate of nucleic-CTMAB- BSA nanoparticles.So the fluorescence intensity is greatly enhanced.The chief characteristics of this thesis are as follows:1.It is found that KI commonly used as fluorescent quenching agent can enhance the fluorescence intensity of morin-fish sperm DNA(fsDNA)system,so KI-morin can selectively recognize fsDNA in double-strand nucleic acids.Based on this,a new sensitive and selective method of determination of fsDNA is developed.The fluorescence enhancement effect induced by KI is considered to originate from the formation of the more favorable structure for the luminescence.2.We find that guanine can enhance the fluorescence of morin.Based on this,a new method for the determination of guanine is proposed.The method is simple, rapid,sensitive and selective.The mechanism study indicates that the fluorescence enhancement of morin is considered to originate from the formation of intermolecular multi-hydrogen bonds between guanine and morin.3.We study the interaction mechanism of Epinephrine-NaOH-Actone-DAN -β-CDx using the techniques including fluorescence,absorption,and CD.The inclusion constant and stoichiometric ratios in the system are calculated based on the "double reciprocal method".In addition,the action of acetone in both the fluorescence enhancement and the inclusion of this system are proposed.4.It is found that the BSA nanoparticles can emit new fluorescence peak at 430nm,which is considered to be the fluorescence peak of BSA aggregate,its intensity is greatly enhanced by nucleic acids in the presence of CTMAB.Based on this,a new method for the determination of nucleic acid is proposed.The fluorescence enhancement of the system is considered to originate from both the formation of large BSA aggregate and the hydrophobic microenvironment provided by nucleic acid and CTMAB for BSA nanoparticles. |
PDF Full Text Request