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.
