Characterization of the human salivary basic proline-rich protein complex by a proteomic approach

Thirteen samples of human normal whole saliva were analyzed by RP-HPLC-ESI-MS and MALDI-TOF-MS to investigate the basic proline-rich protein complex. Between known basic-PRPs the P-B, P-C (or IB-8b), P-D (or IB-5), P-E (or IB-9), P-F (or IB-8c), P-H (or IB-4), IB-6, II-2, IB-1, and IB-8a glucosylated were identified, whereas the II-1, IB-7, PA, and D1-A peptides were not detected. Some detected masses not attributable to known basic-PRPs were putatively ascribed to II-2 and IB-1 nonphosphorylated, II-2 and IB-1 missing the C-terminal arginine residue, and the 1-62 fragment of IB-6, named P-J peptide. A correlation matrix analysis revealed a cluster of correlation among all the basic PRPs (apart from the P-B peptide) which is in agreement with their common parotid origin.