What is the function of adding BSA as buffer in Biotin-Streptavidin system? It is stated that I need to wash streptavidin with buffer containing BSA. And also, I will use some kinds of buffer :

Buffer 1: 10 mM MOPS/KOH pH 7.0, 50 mM KCl

Buffer 2 = Buffer 1 + 2 mM Magnesium Chloride

Buffer 3 = Buffer 2 (4 ml) + 10 mg/ml (final conc.) + bovine serum albumine (BSA)

Buffer 4 = Buffer 3 + 2 mM ATP (final conc.)

Why I need those buffers?

I am going to analyse ATP motor in cell.

Thanks a lot