A preliminary comparative analysis of the H. sapiens saliva proteome between cysteine fractionation,performic acid oxidation LC/MALDI/MS/MS and LC/ESI/MS/MS

We present a comparative study between LC/MALDI/MS/MS and LC/ESI/MS/MS. Diagnostic biomarkers in saliva have been identified for monitoring caries, periodontitis, oral cancer, salivary gland diseases, and systemic disorders e.g. hepatitis and HIV[1]. Saliva is similar to serum in that there are a small number of highly abundant proteins and many low abundance proteins. There are 35 previously identified salivary proteins [1-4]. We prepared a representative sample of cysteine containing peptides and oxidised them to improve their fragmentation under MALDI conditions. In total 20 proteins were identified with 6 been identified by both methods. Surprisingly there was little overlap in the peptides used to identify the proteins between the two methods