Amino acid composition of experimental salivary pellicles

The amino acid compositions of pellicles formed in vitro from submandibular, parotid, and mixed saliva were determined and compared. Samples of the total pellicles as well as the relatively acid-soluble supernates and acid-insoluble sediments were collected and analyzed. In each instance striking differences in composition between the pellicle and the saliva from which it was formed indicate that pellicle formation is a highly selective process. The similarity in composition of the total and fractionated submandibular-parotid pellicle samples indicated a representative dissolution of the total mixed pellicle in the collection acid, rather than a preferential dissolution of part of the total pellicle. In the case of the pellicles formed from the isolated submandibular and parotid salivas, the supernate and the total pellicle were quite similar in composition, but differed somewhat from the sediment. Those results indicate that most of the salivary pellicle is soluble in the dilute acid used to collect the pellicle, and that a portion of the total submandibular or parotid salivary pellicle dissolves preferentially. The compositions of the total parotid pellicle and the parotid supernate and sediment were remarkable similar to the counterparts formed from submandibular saliva alone, suggesting similar origins and mechanisms of formation.