Abstract
Concerning the purification and amino acid composition of human saliva, Petit and Jollès (1963) first purified lysozyme from human whole saliva and reported that its amino acid composition was somewhat different from that of hen egg-white lysozyme. More recently, Balekjian, Hoerman and Berzinskas (1969) has demonstrated that the parotid lysozyme has a composition which varies especially with respect to tyrosine, cystine and glutamic acid content. This communication was designed to confirm the amino acid composition and molecular weight of lysozyme from human parotid saliva.
About eight liters of human parotid saliva were collected from healthy adults with the device according to the method of Keene. Parotid lysozyme was purified to 525-fold by the procedures involving ammonium sulfate fractionation, DEAE-cellulose and CM-cellulose column chromatography, Sephadex G-75 gel filtration and adsorption on Amberlite CG-50 resin. The homogeneity of the purified sample was determined by both ultracentrifugation and disc electrophoresis. It had a specific activity 3.5 times greater than that of hen egg-white lysozyme and an amino acid composition which varied especially in regard to tyrosine, serine and glutamic acid content. The molecular weight was estimated to be around 14, 300.
