The Estimation of Polypeptide Chain Molecular Weights by Gel Filtration in 6 M Guanidine Hydrochloride

Abstract Gel filtration of reduced protein polypeptide chains in 6 m guanidine hydrochloride has been evaluated as a means of estimating protein or protein subunit molecular weights as suggested by Davison (Science, 161, 906 (1968)). As a gel filtration medium, 6% agarose permits useful molecular weight estimates between the extreme limits of 80,000 and 1,000. Provided weight rather than volume is used to measure elution position, excellent precision and accuracy can be obtained. A plot of log molecular weight versus elution position yields a sigmoidal curve from which molecular weights can be estimated with an accuracy of 7% in the nearly linear portion of the curve (40,000 to 10,000 molecular weight) and 10% at the extreme calibration limits.