ELECTROPHORETIC ANALYSIS OF STIMULATED CAT PAROTID-SALIVA

The proteins of parasympathetically stimulated cat parotid saliva were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and high resolution two-dimensional electrophoresis (2-DE) . SDS-PAGE revealed up to 30 polypeptide bands in microliter volumes o f unconcentrated saliva. The patterns were highly reproducible and cha racterized by prominent bands of M(r) 57000, M(r) 30000 and M(r) 15000 . The major protein (M(r) 30000) appeared as a dimer (M(r) 60000) when electrophoresed under nonreducing conditions but dissociated into its monomeric form when the SDS concentration of the denatured samples wa s increased from 1 to 5%. This indicates a noncovalent association. Th e protein patterns of saliva from different cats differed slightly but sequential samples from the same cat (collected during 90 min of stim ulation) showed little change in protein pattern apart from a fall in total protein content. Following 2-DE, the major protein (M(r) 30000) appeared as a complex array of at least eight spots in two tiers (pI 5 .2-6.2; M(r) 28000 and 32000). The characteristics of this protein are discussed with reference to allergy to cats.