THE SULPHYDRYL CONTENT OF β-LACTOGLOBULIN

Abstract

The reaction of sulphydryl groups of β-lactoglobulin with N-ethylmaleimide, p-chloromercuribenzoate, and iodoacetic acid has been studied. Using N-ethylmaleimide with native and sodium dodecyl sulphate denatured protein, a value of 2.3 groups of sulphydryl per mole of protein was obtained. A value of 2.15 moles of sulphydryl per mole of protein was obtained from reaction with p-chloromercuribenzoate but lower values were obtained after urea denaturation. The reaction of iodoacetic acid was followed by the determination of residual sulphydryl by the p-chloromercuribenzoate method.