R. Signer

Countercurrent distribution in protein chemistry.

Publisher Summary The chapter discusses the countercurrent distribution in protein chemistry. The chapter presents the basic principles of countercurrent distribution, including the distribution law of Nernst and Partition Coefficient, multiple distribution, calculation of the fundamental process, and distribution curves. The two types of distributions are— namely, batteries in which the phases are discontinuously displaced, and columns in which the phases are in continuous flow. The efficiency of a distribution column or battery is judged by its separative power and its capacity. The methods for increasing the number of transfers over the number of distribution cells consist in the withdrawal of fractions at one or both ends of the battery. These possibilities are discussed briefly. A few typical examples of the application of countercurrent distribution are discussed in this chapter. Successful application of countercurrent fractionation requires a suitable two-phase solvent system, in which both phases exert a solvent action on the components of the mixture. The solutes should neither suffer decomposition in the solvent system nor should proteins undergo denaturation in it. Countercurrent distribution has been successfully applied to the isolation of amino acids, peptides, and polypeptides. However, large-scale equipment for fractionation of amino acids is justified only when it is employed for preparative purposes.