Robust Estimation of Standard Curves for Protein Molecular Weight and Linear-duplex DNA Base-pair Number After Gel Electrophoresis

An accurate procedure for estimating linear-duplex DNA base-pair numbers and protein molecular weights after electrophoresis in single concentration gels is presented. A robust modified hyperbola was found to be superior for determining molecular weights and base-pair numbers for a set of known standards when compared with the conventional log transformation and a similar hyperbolic model. We describe the use of a soft laser-scanning densitometer to measure band-migration distances of wet, stained polyacrylamide gels for proteins and photographic negatives of agarose gels containing DNA stained with ethidium bromide. This automated densitometric method was more accurate than existing methods. A BASIC computer program detailing the procedure is included.