LYSOZYME OF HUMAN PAROTID GLAND SECRETION - ITS PURIFICATION AND PHYSICOCHEMICAL PROPERTIES

Lysozyme was isolated from human parotid saliva (HPL) and chromatographically purified. The amino acid composition of the purified HPL was similar to other human lysozymes. The minimum molecular weight calculated from the amino acid composition compared favorably with values reported from other lysozymes (1). The molecular weight determined by analytical ultracentrifugation was in the range from 15,000 to 17,000, depending on the value used for the partial specific volume in the calculation. The specific activity of HPL was 2.5 times greater than that of hen's egg white lysozyme (HEL). Accordingly, the true concentration of the enzyme in the native parotid gland secretion is about 0.5 mg per 100 ml and thus lower than that based on enzyme assay using HEL as the standard of reference. © 1969.