Competitive Binding Equilibrium Study Between Serum Albumin And Cu (Ⅱ),Mn(Ⅱ) Binding Study Of HSA Or BSA And Silver Nanoparticle With UV

Part I With UV spectroscopy and equlibrium dialysis,the competitive binding capabilities of Cu(II) and Mn(II) to human serum albumin (HSA) or bovine serum albumin (BSA) at physiological pH have been studied. The Scatchard analysis of the competitive binding equlibrium indicates that there exists one strong binding site of Cu(II) and Mn(II) in HAS and BSA,which is at the tripeptide segment of N-terminal of protein. The binding capabilities of Cu(II) to this binding site is stronger than that of Mn(II). The two ions have some common weak binding sites in HAS and BSA. And there exists antagonism effect between the two ions. With UV spectroscopy scaning at physiological pH,the absorption peaks of the system Cu(II)-Mn(II)-serum albumin were caused by the LMCT transition,which chiefly show the effect of Cu(II).With the increase of the concentration of the system Cu(II)-Mn(II)- serum albumin at molar ratio 1:1:1,its coordination centre changes from a pentacoodinated sqaure-pyramid into tetracoodinated sqaure-planar. When the concentration of the serum albumin fixed and the concentrative ratio of metal ions and serum albumin increased,there exists similar configuration of the coordnation centre.Part II With UV spectroscopy scaning,the binding of silver nanoparticle to HSA or BSA has been studied. At different pH,the analysis to the capability that serum albumin encapsulates silver nanoparticle shows that serum albumin binds to silver nanoparticle mainly by electrostatic force. With UV spectro- scopy tracking experiment,It has been found that the binding of serum albumin to silver nanoparticle has double hysteretic effect,which means not only serum albumin's encapsulating silver nanoparticle but the configuration transition of serum albumin induced by serum albumin binding with silver nanoparticle. The velocity constants that serum albumin encapsulates silver nanoparticle and corresponding thermodynamic parameters have been calculated and discussed. It was found at the same time that serum albumin binding with silver nanoparticle would possibly induce HAS or BSA to give a slow conformational transition of serum albumin(B-B' transition). The rate constants and thermodynamic parameters of the configuration transition have been measured and discussed .