Abstract: Using titanium dioxide is a very good strategy for the phosphopeptide enrichment. There are many other factors can affect the enrichment efficiency, and the optimization of parameters was needed for better enrichment results. In this study, the peptide mixtures of six standard proteins were used as the model samples to evaluate and optimize the parameters such as the proportion of acetonitrile and trifluoroacetic acid in loading buffer and the TiO2-to-peptide ratio. The results showed that 80%(v/v) acetonitrile, 1%(v/v) trifluoroacetic acid and 40:1 (m/m) TiO2-to-peptide ratio were the optimum parameters to obtain the best enrichment selectivity and maximum phosphopeptides identification. For the first time, the optimum enrichment conditions were applied for the phosphoproteome analysis of the Thermoanaerobacter tengcongensis, an anaerobic, saccharolytic, thermophilic bacterium isolated from a hot spring in Tengchong, China, and 25 phosphorylated proteins were identified in the preliminary experiment. The results provided a reference for further study on this organism survived under extreme environment.

Key words: enrichment, mass spectrometry (MS), phosphopeptide, proteome, Thermoanaerobacter tengcongensis, titanium dioxide, liquid chromatography (LC)