Research On The BSA/anti-BSA Interactions In Drug Solutions Based On Self-assembly And AFM

A molecular level understanding of protein-protein interactions is fundamentally important inthe life sciences. A number of human diseases are closely related to the protein-proteinassociation or dissociation events and thus probing and characterizing these interactions havebecome increasingly significant in the development of novel drugs and medical diagnostics. Inthis article, we investigated the interactions between BSA and rabbit anti-BSA by using singlemolecule force spectroscopy and surface plasmon resonance. The main contents are as following:F_irst, we immobilized the BSA and anti-BSA on the AFM substrate and AFM-tip by the methodof self-assembly and measured the adhesion force between BSA and anti-BSA in different kindsof drug solutions by AFM. By using Poisson statistics method, we obtained the the specific forcebetween a single pair of BSA and anti-BSA, F_iand the nonspecific force, F₀in PBS and thethree drug solutions. In PBS, F_i=98pN, F₀=48pN. In tylosin solution, F_i=54pN. Insulphathiazole sodium solution, F₀=90pN. Second, we obtained the association rate of BSA andanti-BSA in different kinds of solutions by SPR. In PBS, ka=7.0710³M^-1s^-1. In tylosin solution,ka=3.3410³M^-1s^-1. In sulphathiazole sodium solution, ka=8.9710³M^-1s^-1. Third, weinvestigated the effect of concentration and structure in the same types of drug to the interactionforce between BSA and anti-BSA by AFM. The results show macrolide antibiotics may coveravailable binding sites and weaken the specific adhesion force between BSA and anti-BSA.Sulfonamides antibiotics may increase the solution IS and compress the thickness of theelectrostatic double layer surrounding proteins, and finally result in an increase in nonspecificadhesion. Quinolones antibiotics as a kind of small nonionic drug may not affect the interactionsof BSA and anti-BSA because of neither bigger spatial structure of tylosin molecule norincreasing IS in solution.