Abstract
Protein-protein interactions play crucial roles in numerous biological processes. However, it is still challenging to evaluate the protein-protein interactions, such as antigen and antibody, in the presence of drug molecules in physiological liquid. In this study, the interaction between bovine serum albumin (BSA) and rabbit anti-BSA was investigated using atomic force microscopy (AFM) in the presence of various antimicrobial drugs (sulphathiazole sodium, tylosin and levofloxacin) under physiological condition. The results show that increasing the concentration of tylosin decreased the single-molecule-specific force between BSA and rabbit anti-BSA. As for sulphathiazole sodium, it dramatically decreased the specific force at a certain critical concentration, but increased the nonspecific force as its concentration increasing. In addition, the presence of levofloxacin did not greatly influence either the specific or nonspecific force. Collectively, these results suggest that these three drugs may adopt different mechanisms to affect the interaction force between BSA and rabbit anti-BSA. These findings may enhance our understanding of antigen/antibody binding processes in the presence of drug molecules, and hence indicate that AFM could be helpful in the design and screening of drugs-modulating protein-protein interaction processes.
Highlights
A molecular level understanding of protein-protein interactions is fundamentally important in the life sciences
We investigated the interaction between Bovine serum albumin (BSA) and rabbit anti-BSA when it was measured by atomic force microscopy (AFM) in either phosphate buffered saline (PBS) or PBS solution containing one of the three antimicrobial drugs under physiological conditions
Provided that the measured total interaction force is composed of a finite number of discrete interacting antigen-antibody pairs within a fixed contact area, the specific force between a single antigen-antibody pair (Fi) and possible nonspecific interaction force (F0) can be derived from the slope and interception of the linear regression curve of the variance versus the mean of the measured total adhesion force as σm2 = μmFi − FiF0 [27]
Summary
A molecular level understanding of protein-protein interactions is fundamentally important in the life sciences. A number of human diseases are closely related to the protein-protein association or dissociation events and probing and characterizing these interactions have become increasingly significant in the development of novel drugs and medical diagnostics [1,2,3,4] Different solution conditions, such as pH, temperature, ion species, and strength, may influence the protein-protein interactions as previous studies have demonstrated [5,6,7]. The computer studies do not provide more detailed information on forces at nanoscale-to-molecular scale that influence protein-protein interactions, which would allow us to better understanding the factors of drug molecules affecting the interactions It Bovine serum albumin (BSA) is the major protein constituent of blood plasma and it facilitates the disposition and transport of various exogenous and endogenous ligands to the specific targets. No investigations have been made of the mechanical behavior of BSA in the presence of these drugs
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