Studies on Polypeptides and Amino Acids by Countercurrent Distribution

Because of the importance of amino acids, poly-peptides and proteins an attempt o apply nearly every method thus far devised by chemists for frac-tionation, characterization a d proof of purity of or-ganic substances has at some time been made. It is thus only logical to attempt application of the method and viewpoint of "Countercurrent Distribu-tion. " Perhaps some definition of countercurrent distribution should be given for the benefit of those who are not familiar with the method (Craig and Post, 1949) and the published work which has dealt mainly with antimalarials, penicillins, fatty acids, antibiotics, pyrimidines, streptomycins etc. The method depends on a stepwise fractionation process involving the distribution of solute between two