The purification of kallikrein from human whole saliva

A quick and simple procedure is described for purifying kallikrein from human whole saliva. The enzyme has been purified about 2700-fold with a yield of approx. 30%. The procedure is based on the immediate fractionation of saliva by ion exchange chromatography. This is followed by a combination of affinity and high performance liquid chromatography. The results indicate that another protein component binds to the enzyme at pH 8.0. The homogeneity of the enzyme has been demonstrated by gel electrophoresis in the absence as well as in the presence of sodium dodecylsulfate. A mol. wt of 40,100 +/- 1800 has been calculated from gel electrophoresis experiments. Sedimentation equilibrium in an analytical ultracentrifuge gave a mol. wt of 39,700. The amino acid composition has been determined and it confirms that the enzyme has a low isoelectric point. The presence of tryptophan has been demonstrated by absorption and fluorescence spectroscopy.