Study On The Denaturation Of Bovine Serum Albumin And The Interaction Between Five Classes Of Nitrogenous Compounds With Bovine Serum Albumin

It is well know that animal blood contains a lot of serum albumin,which forms the basic protein in the serum.BSA is a globular protein and and has a compact ellipsoid structure.The stability of this structure originates mainly from hydrophobic interactions.The existence of 583 amino acids and 17 disulfide bridges in BSA has been reported.BSA is markedly polar with a potential for 100 negative and 82 positive charges at neutral pH.Thus the net negative charge of BSA is-18.The charge distribution is not uniform.Fluorescence techniques are very helpful in protein-small molecule interactions due to their high sensitivity,rapidity and ease of implementation.The fluorescence measurements can provide some useful information about the binding of small molecules to protein such as binding mechanism,binding mode,binding constants and binding numbers.The conclusions from this job can be summarized as below:1.The interaction between varenicline tartrate and bovine serum albumin was investigated.The quenching mechanism between varenicline tartrate and bovine serum albumin was clarified.The binding constants and the number of binding sites were deduced to 2.27×103 L·mol-1 and 1.The binding distance was calculated to be3.68 nm,which means that there was non-radiative energy transfer from varenicline tartrate to bovine serum albumin during the process.2.A novel porphyrin derivative(PFP)interaction with bovine serum albumin(BSA)was investigated by fluorescence and ultraviolet spectrophotometer.The experimental result revealed that the quenching in PFP–BSA system is combined quenching.the r=3.67(r < 7)nm demonstrated that there was no-radiative energy transfer happened during the whole process from PFP to BSA.3.Four kinds of pyrrolizine derivatives(SPD-1,SPD-2,SPD-3,and SPD-4)interaction with bovine serum albumin was investigated by multiple spectroscopic techniques.Fluorescence spectroscopy analysis showed that in SPD-BSA system static quenching govern the interaction mainly.Furthermore,The thermodynamic parameters(?H,?G and ?S),which were determined according to Van't Hoff equation,indicated that the binding process is spontaneous and the hydrophobic forces is playing a major role between SPD-2,SPD-3 and BSA,but the electrostatic interactions playing a major role between SPD-1,SPD-4 and BSA.The efficiency of energy transfer(E)and binding distance(r),which were calculated according to F?rster non-radioactive energy transfer theory,demonstrated that there wasno-radiative energy transfer from SPD-1,SPD-2,SPD-3,and SPD-4 to bovine serum albumin during the process.4.We aim to investigate the changes of bovine serum albumin induced by urea from various angles.The study demonstrated that with the addition of urea,the tertiary structure of bovine serum albumin unfolding gradually,the unfolding process give rise to the increased level of water-exposed of the protein.Furthermore,the native and denatured bovine serum albumin interaction with 32?-NOR were investigated in the absence and presence of 8 mol·L-1 urea.The higher Stern–Volmer quenching constant(Ksv)indicated that the quenching process for native bovine serum albumin is easier than the denatured bovine serum albumin,also,binding parameters(Ka)of the interaction system illustrated that the native bovine serum albumin has stronger combination capacity than the denatured bovine serum albumin.The fluorescence lifetime studies demonstrated that the denaturation of bovine serum albumin results in the faster fluorescence decay and water-exposed of the protein.The efficiency of energy transfer indicated that the native bovine serum albumin has a shorter binding distance with 32?-NOR than the denatured bovine serum albumin.5.The work investigated the interaction between CNNCP and BSA in pH=7.43,pH=4.0,pH=2.0,and pH=11.0.The Stern–Volmer quenching constant(Ksv),binding parameters(Ka)and the efficiency of energy transfer decreased with the rise pH.The binding site of CNNCP on BSA mainly is located in site I.The binding distance(r)were less than 7 nm in pH=7.43,pH=4.0,and pH=2.0,which indicated that there was no-radiative energy transfer from CNNCP to bovine serum albumin.