Purification of Mammalian Kallikreins, Kininogens, and Kinins

Abstract

Many reports describing procedures for purifying the components of the kallikrein-kininogen-kinin system have appeared since Frey and co-workers (Frey, 1926; Frey and Kraut, 1926) initiated the work on urinary kallikrein which led to the discovery of this system. However, not until the advent of high-resolution separation methods in the last twelve years has much progress been made toward the isolation of these proteins in pure and biologically active form. The older methods, such as the Cohn alcohol fractional precipitation of plasma proteins (Cohn et al., 1946), tend to be nonspecific by present-day standards and thus inefficient, and to cause denaturation and hence loss of activity. The newer methods usually employ mild conditions of pH, temperature, and solvent, and so favor the retention of biological activity. Such methods also embody a continuous countercurrent principle which magnifies small differences between closely similar compounds, thus making possible high resolution and, as a corollary, high recovery. Outstanding examples are ordinary and recycling gel filtration; gradient elution chromatography on columns of ion exchangers and hydroxyapatite; preparative polyacrylamide gel electrophoresis and isoelectric focusing; and ultracentrifugation in density gradients. Reviews of the theory and applications of these techniques appear in alternate years in Analytical Chemistry [see Anal. Chem. 40 no. 5, IR-620R (1968)]. The reader is referred also to the useful book on chromatography edited by Heftmann (1967). Future progress in the purification of proteins and other macromolecules will probably lie chiefly in the further development of affinity adsorption methods (Cuatrecasas et al., 1968). Examples are the use of immunoadsorbents for the purification of antigens and antibodies and the use of inhibitor and enzyme columns for the purification of enzymes and inhibitors respectively (Fritz et al., 1967 b, c, 1968, 1969 a, b).