Protein extraction from diatom for MALDI analysis

Abstract

This study aim was to investigate protein extracted from natural silica collected from diatoms using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) method, alongside with the investigation on which extraction reagent was the most suitable for this analysis. Diatoms are one of the main group of algae that can produce natural silica particles from the cell wall, which can be used as a natural sorbent. Biosilica is obtained by removing the organic part from diatom cells. The biosilica particle is strictly defined (e.g. by the structure of pores) and possess active functional groups such as carboxyl, amine. For further analysis of organic deposit of biosilica, a MALDI analysis was carried out. This method is widely used for a fast peptides/protein analysis as well as microorganism identification. For protein extraction, five different combination of solutions were used: 0,1% ACN, 0,1% TFA, TA30, 5% TFA and 0,1% TFA/ACN solutions were used. For MALDI analysis silica extractions were spotted on MALDI target and analyzed with Bruker Ultraflex II TOF/TOF MALDI mass. The analysis of peptides from biosilica showed, that almost all peaks contained modified peptides residue or additions to matrix molecules.