Gel Electrophoresis of Amylose in the Presence of Sodium Dodecyl Sulfate

Abstract

It has been shown that sodium dodecyl sulfate (SDS) is capable of forming stable complexes with amylose and that fractionation of short-chain amyloses can be effected by SDS-gel electrophoresis. Using a well-defined amylose fraction (molecular weight 4,000), the thermodynamic parameters pertaining to SDS-amylose interaction have been evaluated by means of frontal gel chromatography. The results are as follows: association constant (K) = 5.0×10³M⁻¹ at 25° (pH 9.4); standard free energy change (ΔG°)=−5.1 kcal/mole ; standard enthalpy change (ΔH°)=−5.8 kcal/mole ; standard entropy change (ΔS°)=−2.3 (e.u.) and the maximum number of binding sites for SDS (n)=1. In the presence of 0.5–1% SDS, amylose migrates toward the anode upon gel electrophoresis, giving a compact band. High resolution of amylose fractions (released by treatment of amylopectin with debranching enzyme) has been attained using pore-size gradient gel electrophoresis.