Gel filtration of proteins, peptides and amino acids

Abstract

1. 1. Mixtures of proteins, peptides and amino acids can be fractionated by filtration through beds of dextran gel containing only small amounts of carboxylic groups. 2. 2. Group separations are readily achieved. In highly cross-linked dextran proteins and large peptides move together ahead of amino acids. In dextran gels of low degree of cross-linking peptides and even proteins may be retained on the columns, so that a fractionation of substances within these groups may be obtained. 3. 3. Basic peptides and amino acids move slowly through the gels in certain basic solvents such as 1 M pyridine and faster in acidic solvents such as 1 M acetic acid. For acidic peptides and amino acids the influence of the solvents mentioned appears to be the reverse of that for the basic compounds. 4. 4. Aromatic substitution has a marked effect on the migration through the gels. The relative speed of dinitrophenylated amino acids is highly dependent on the buffer used. Such influence of the buffer was not noticed for phenylalanine, tyrosine and tryptophan, although these compounds are retarded to a different extent. 5. 5. When the columns are properly prepared, symmetrical distribution of each compound is always obtained. 6. 6. The column capacity is very high compared to other similar column methods (chromatography and zone electrophoresis). 7. 7. The reproducibility is very good. 8. 8. The gels are easily regenerated in the columns and may be used daily over a period of months without detectable deterioration. © 1960.