The protein composition of ferret parotid saliva as revealed by high-resolution electrophoretic methods

Ferret parotid saliva has been analysed using sodium dodecyl sulfate-polyac rylamide gel electrophoresis (SDS-PAGE) and two-dimensional electrophoresis (2-DE) to determine, for the first time, its protein composition. SDS-PAGE , in combination with Coomassie Brilliant Blue (CBB) staining, revealed up to 20 bands and the patterns were characterised by major protein constituen ts of M-r 105 000, 51 000, 47 000, 33 000, 22 000 and 16 400 common to all samples from all animals. Sequential samples collected from the same animal during prolonged stimulation of the parasympathetic nerve (40 min at 40 Hz ) showed subtle but reproducible protein changes. Saliva collected from dif ferent animals varied widely in the amount of a protein M-r 66 000. 2-DE, i n combination with silver staining, revealed up to 300 spots and the patter ns were characterised by major protein constituents of M-r 105 000 (p/6.3-7 .2), M-r 66 000 (p/4.7-5.3), M-r 51 000 (p/5.0-5.7), M-r 47 000 (p/6.0-7.5) , and M-r 33 000 (p/4.7-6.0). Many of the polypeptide spot clusters consist ed of one or more horizontal strings of spots suggesting extensive microhet erogeneity. Both SDS-PAGE and 2-DE indicated that the protein patterns of f erret parotid saliva evoked by electrical stimulation of the parasympatheti c nerve in the absence or presence of atropine are similar, i.e., the prote in composition of the atropine-resistant nonadrenergic, noncholinergic (NAN C) secretion is similar to that of saliva evoked in the absence of muscarin ic receptor blockade.