Study On The Supramolecular System Based On Amphiphilic Molecules And Bovine Serum Albumin

The study of protein-surfactant mixtures has been a subject of great interest.Firstly,they are the substance in common use,and both of them are amphiphilic molecules,thus they are easy to interact with each other.The complex of protein and surfactant has been widely used in the fields of biology,medicine,food,cosmetics etc at present.secondly,with the development of science and technology,some new surfactants have been synthesized.Because different surfactants have distinct difference,the study results of interaction between surfactants and protein can not be of universality.Based on the above reasons,the study on the interaction between surfactant and protein has important theoretical and practical significance.Interaction between four kinds of different types of surfactants and bovine serum albumin?BSA?in Na₂HPO₃-NaH₂PO₃ buffer solution?pH=7.4?were studied by using fluorescence spectroscopy,UV absorption spectroscopy and circular dichroism spectroscopy in this paper.Effects of the surfactant structure and concentration on the interaction were examined,and the binding mechanism and mechanism of surfactant and BSA were elucidated.This thesis is divided into five parts.In the first section,the basic knowledge of protein and surfactant,and the research progress and significance of the interaction between surfactant and protein are summarized.In the second section,we studied the interaction between benzenesulfonate Gemini surfactant?9AB-s-9AB,s=4,6?and BSA,at the same time,sodium dodecyl sulfate?SDS?which was a single chain anionic surfactant was selected to study comparatively.The results of endogenous fluorescence showed that both the alkyl benzene sulfonate Gemini surfactants?9AB-s-9AB,s=4,6?had a quenching effect on the fluorescence of BSA.With the increase of the concentration of surfactant,the fluorescence quenching of BSA was enhanced and the maximum emission wavelength was blue shifted.Synchronous fluorescence showed that the addition of surfactants mainly affected the tryptophan?Trp?residues of BSA,and it was inferred that the conformation of BSA has changed to a certain extent.Combined with the Stern-Volmer equation and the UV absorption spectrum,the main reason for the fluorescence quenching of BSA was static quenching.In addition,the results of circular dichroism showed that the interaction between 9AB-s-9AB and BSA was significantly higher than that of SDS and BSA,and the interaction between 9AB-s-9AB and BSA was dependent on the length of spacer alkyl chain.The longer the alkyl chain was,the stronger it binded to BSA.In the third section,the long-chain head quaternary ammonium Gemini surfactant[C₁₂C₄C₁₂?C_n?Br₂,n=1,2,3,4]was selected to interact with bovine serum albumin?BSA?.The results showed that all the long-chain quaternary ammonium Gemini surfactants had a quenching effect on the fluorescence of BSA,the addition of C₁₂C₄C₁₂?C_n?Br₂ mainly affected the tryptophan?Trp?residues of BSA.With the increase of the concentration of C₁₂C₄C₁₂?C_n?Br₂,the fluorescence quenching of BSA was enhanced and the maximum emission wavelength was blue shifted.The reason for this fluorescence quenching was that C₁₂C₄C₁₂?C_n?Br₂ formed a complex with BSA and caused static enhancement,which belonged to the static quenching process.The binding of C₁₂C₄C₁₂?C_n?Br₂toBSAfollowedtheorder:C₁₂C₄C₁₂?Et?Br₂<C₁₂C₄C₁₂?Pr?Br₂<C₁₂C₄C₁₂?Bu?Br₂<C₁₂C₄C₁₂?Me?Br₂,which indicated that the interaction between C₁₂C₄C₁₂?C_n?Br₂and BSA had an important relationship with the type and chain length of head alkyl chain in the molecule.In the fourth section,the interactionbetweenp-Dimethylphenylpiperidine quaternary ammonium Gemini surfactant[Pi?C_m?,m=12,14,16]andBSA has been studied.The results showed that Pi?C_m?had a quenching effect on the fluorescence intensity of BSA.With the increase of the concentration of surfactant,the fluorescence quenching of BSA was enhanced and the maximum emission wavelength was blue shifted,and the fluorescence quenching phenomenon included a static quenching process.Pi?C_m?mainly affected the Trp residues in the BSA molecule and leaded to a change in the conformation of BSA.Under the same conditions,the interaction between Pi?C_m?and BSA was dependent on the length of the alkyl chain of the hydrophobic tail chain in the molecule,and the longer the hydrophobic alkyl chain was,the stronger it binded to BSA.The interaction between the three surfactants and BSA molecule followed the rule:Pi(C₁₂)<Pi(C₁₄)<Pi(C₁₆).In the fifth section,we selected Bola surfactant[Bola?C_n?,n=1,2,3]interacted with BSA.The results of fluorescence spectrum showed that Bola surfactants have stronger interaction with BSA than single-chain cationic surfactants.All the Bola surfactant[Bola?C_n?,n=1,2,3]had a quenching effect on the fluorescence of BSA.Bola?C_n?mainly affected the Trp residues in the BSA molecule and leaded to a change in the conformation of BSA.With the increase of the concentration of surfactant,the fluorescence quenching of BSA was enhanced and the maximum emission wavelength was blue shifted.Combined with the Stern-Volmer equation and the UV absorption spectrum,the main reason for the fluorescence quenching of BSA was static quenching.In addition,the CD spectra showed that the interaction of Bola surfactant with BSA was in the following order:Bola?Me?<Bola?Et?<Bola?Pr?.It can be deduced that the effect is related to the length of the head alkyl chain in the molecule,and the longer the head alkyl chain was,the stronger it binded to BSA.