The purification and partial characterization of human salivary kallikrein

Quantification of human myeloperoxidase in oral fluids

Peroxidase activity in human whole saliva is derived from salivary peroxidase and myeloperoxidase. Present spectrophotometric assays are relatively non-specific and influenced by ions present in salivary secretions, resulting in an over and/or underestimation of peroxidase activities. Specific polyclonal or monoclonal antibodies would greatly simplify the identification of salivary peroxidase and myeloperoxidase in human saliva and determine the relative contribution of each enzyme to the total peroxidase activity in human saliva. In the present study, a highly purified preparation of myeloperoxidase was used to raise polyclonal antibodies against the antigen. The antibodies were purified and extensively characterized in terms of their ability to interact with the antigen, with other mammalian peroxidases, and with other proteins present in salivary fluids. The antibodies recognized only myeloperoxidase and did not cross-react with any of the substances tested, showing that these antibodies can be used to detect and differentiate myeloperoxidase from other peroxidases in saliva. We have also developed and tested a sandwich ELISA which can be used in a clinical setting to quantify myeloperoxidase in whole saliva and gingival crevicular fluid.

Purification and characterization of a glycosylated proline-rich protein from human parotid saliva

1. A glycosylated proline-rich protein (GPRP) was purified to homogeneity by subjecting parotid saliva to immunoaffinity, cation exchange, affinity and hydrophobic chromatography. 2. The purified GPRP had a molecular weight of 78 kDa as analyzed by SDS-PAGE. 3. The amino acid analysis revealed a preponderance of proline, glycine and glutamic acid/glutamine, which accounted for 77% of the total amino acids. 4. Cysteine, tyrosine or phenylalanine residues were not detected. 5. The glycoprotein contained 34% neutral sugars and the oligosaccharides were rich in mannose and N-acetylglucosamine, indicating that N-linked oligosaccharides were the predominant type of oligosaccharides in the molecule. 6. These observations were confirmed by treatment of the purified glycoprotein with specific N-glycosidase which removed the N-linked oligosaccharides leaving a core protein with an apparent molecular weight of 51 kDa. 7. The isoelectric point of GPRP was approx 7.0 and the molecule was not affected by reduction with 2-mercaptoethanol, indicating that no disulfide linkages were present. 8. The GPRP bound to hydroxyapatite and this binding could be partially inhibited by preincubation of the hydroxyapatite with parotid or submandibular saliva. 9. The purified GPRP also bound to a protein with an apparent molecular weight of 95 kDa present in submandibular saliva.

Plasma half-life and organ uptake ratio of radiolabeled glandular kallikrein in control and nephrectomized rats

The purified rat urinary kallikrein was radiolabeled by lactoperoxidase method and by chloramine T method. Plasma half-life of radiolabeled kallikrein was 5.06 +/- 0.59 (n = 5) min in control rats and 5.24 +/- 0.42 (n = 5) min in nephrectomized rats. There was no difference between two groups. From autoradiogram, main metabolic organs of radiolabeled kallikrein were liver, kidney and spleen. Total uptake of radiolabeled kallikrein in ech organ was the highest in liver (73.2%). The uptake per g tissue of radiolabeled kallikrein in each organ was high in liver (33.0%), kidney (31.4%) and spleen (21.1%). These results suggest that the active kallikrein is metabolized mainly in the liver, and kidney is not so an important organ to metabolize or to eliminate the active kallikrein in plasma. In order to clarify the mode of existence of active kallikrein in plasma, the following experiment was done by using disc gel electrophoresis. Radioactive profile of radiolabeled kallikrein showed one peak (Rf = 1.0), but radiolabeled kallikrein mixed with rat plasma showed two peaks, that is small peak (Rf = 1.0), and main peak (RF = 0.5). The most of radiolabeled kallikrein was bound to plasma protein and only five per cent was in free form. Furthermore, the binding of radiolabeled kallikrein to plasma protein was interfered by the addition of active kallikrein. These results suggest the possibility of existence of kallikrein binding protein in plasma.

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.

AM1, a glycoprotein from the submandibular glands of the mouse, has esterolytic and amidolytic activities

The previously isolated female submandibular glycoprotein AM1 ( Nieuw Amerongen , A.V., Vreugdenhil , A.P. and Roukema , P.A. (1977) Biochim. Biophys. Acta 495, 324-335) has been shown to have hydrolytic activity using N-alpha-benzoyl-L-arginine ethylester (BAEE) and ChromozymR PK as a substrate. AM1 can be secreted in vivo by isoproterenol, and to a lesser extent by carbamylcholine and phenylephrine. Based on BAEE as a substrate, AM1 has an optimum pH of 7.8. In female submandibular glands, about one-third of total esterolytic activity resided in glycoprotein AM1, but in male submandibular glands, less than 3%. The Km value of glycoprotein AM1 is 50 microM and its Vmax is 117 mumol/min per mg glycoprotein AM1. The enzymatic activity is not inhibited by Ca2+, Mg2+ and Na+, slightly by Cu2+ and strongly by Hg2+ and phenylmethylsulfonyl fluoride. Glycoprotein AM1 is capable of hydrolyzing ChromozymR PK with a turnover value 20-fold lower than that for BAEE. With ChromozymR PK as a test substrate, glycoprotein AM1 was purified by a factor of 11. With this substrate, glycoprotein AM1 has an optimum pH between 6.6 and 7.6. Also with chromozymR PK as a substrate, the submandibular glands of female mouse showed a much higher activity of glycoprotein AM1 than the submandibular glands of the male mouse. About 75% of all enzymatic activity of female submandibular glands resided in glycoprotein AM1 and in male submandibular glands 22%. The Km value is 57 microM and its Vmax 6.7 mumol/min per mg glycoprotein AM1. From the biochemical characteristics and the localization of glycoprotein AM1, it has been concluded that glycoprotein AM1 is not identical to any of the other described murine submandibular esteroproteinases , such as kallikrein, gamma-subunit of the nerve growth factor, proteinase A and proteinase F.