Peptide purification by gel filtration in aqueous pyridine--ammonia.

A method is described for the purification of peptides by gel filtration on Sephadex. The success of the method is due mainly to the use of 70% ($\text{v}\text{v}$) pyridine-30% ($\text{v}\text{v}$) 1 m aqueous ammonia, an excellent volatile solvent for peptides which does not degrade Sephadex. The method has been used to purify all of the major peptides of cowpea chlorotic mottle virus coat protein, after an initial fractionation by ion-exchange chromatography, and selected separations are used to illustrate the degree of fractionation which can be achieved.