Human Acquired Enamel Pellicle Peptidome

The selective adsorption of salivary components results in the formation of an organic film on the tooth surface known as the acquired enamel pellicle (AEP). Our previous investigation using state of the art proteomics on the protein composition of in vivo AEP has revealed that it contains 130 different proteins based on the presence of at least 2 different tryptic peptides belonging to the same protein (Siqueira et al., 2007). It is known that the oral cavity presents a high proteolytic activity that may affect the structure of the salivary proteins and consequently the AEP may mostly contain peptides of these proteins rather than the intact precursor protein. Objective: To investigate the type and the nature of peptides present in the in vivo formed human AEP. Method: AEP material was collected from 10 volunteers and subjected to sample preparations consisting of a) filtration using a 10kD MWCO membrane and b) gel filtration capillary chromatography. The fractions containing peptides < 10kD obtained by both methods were analyzed by LC-ESI-MS/MS. Result: 98 natural AEP peptides with molecular weights ranging from 933.1 to 3981.4 Da were identified from 22 different proteins. Conclusion: The number of peptides present in AEP appears to be large and this is likely to enhance the functional spectrum of AEP. The presence of small peptides in AEP may be functionally important since structure/function studies of many salivary proteins have shown that specific domains within these native proteins are responsible for biological activities. In the future, the precise function of these AEP peptides needs to be addressed to fully understand the role pellicle plays in the oral cavity. Supported by NIH/NIDCR grants DE05672, DE07652, and DE14950.