The separation of the hexone bases from a protein hydrolysate by electrolysis. 1

Abstract

In a previous communication describing a method for the preparation of glutamic acid, the need of developing cheaper methods for the production of amino acids in quantity was pointed out. This is especially true with respect to the amino acids arginin, histidin and lysin. The cost of reagents and the labor required for the preparation of these amino acids prohibits experimental work in which large quantities of these substances are required.

Some years ago Ikeda and Suzuki 2 described a method for separating certain fractions of the products of protein hydrolysis. Their method has apparently not come into general use and experimental data are not available. On passing direct current through a solution of the protein cleavage products, which is placed in the center of a three-compartment cell, the amino acids are separated into three fractions consisting of (a) the amino acids which are predominantly acid, including aspartic and glutamic acid, which migrate to the anode, (b) the basic amino acids which include arginin, histidin and lysin, and which wander to the cathode, and (c) the remaining amino acids, which on account of the fact that their acid properties are about equally balanced by their basic properties, remain in the center compartment.

Since this method eliminates the reagents which, in other methods, are required in order to separate the hexone bases, experimental work was carried out on a laboratory scale to determine the general applicability of this method to the isolation of the basic amino acids.

The electrolytic cell consists of a rectangular wooden box 3 × 6 × 4.5 inches which was cut into three approximately equal vertical sections. The membranes separating the compartments consist of strips of linen cloth which were coated with gelatin by immersion in a 30 per cent. solution of this substance and the gelatin was subsequently fixed by allowing the strips to remain in formalin over night.