Quantitative and qualitative analyses of human salivary micelle-like globules

In the present study we examined the protein proportion and amino acid profile of the salivary micelle-like globules (SMGs) of human whole saliva and parotid saliva (HWS, HPS). Saliva and SMG samples from each subject (clarified HWS and HPS from 6 subjects, and unclarified HWS from 3 subjects) were analysed for amino acids using standard acid hydrolysis procedures. HPS, clarified HWS and the respective supernatant samples (remaining after removal of the SMGs) were also measured for protein using the micro-Kjeldahl method. SMGs from clarified and unclarified HWS made up 4.7% and 19.7%, respectively, of the total salivary protein based on amino acid analyses. With the micro-Kjeldahl method SMGs from clarified HWS made up 7.3% of the total saliva protein. SMGs isolated from HPS were found in only small amounts. The amino acid profile for the SMGs was strikingly similar to that known for the 2-h pellicle, and differed significantly from HWS or HPS. The results support previous morphological studies indicating that the SMGs represent a major component of the newly formed pellicle.