New strategies for the fast, efficient, and environmentally friendly extraction of proteins are required to isolate desired bioactive compounds from a technological point of view. In this study, utilization of the pressurized water extraction (PWE) at low temperature (40 °C) for isolation of mistletoe proteins was investigated. PWE effectiveness, based on protein fingerprints, were compared with those obtained by conventional extractions using 10 mmol L-1 Tris-HCl buffer pH 8.3, 50 mmol L-1 phosphate buffer pH 7, or deionized water. The extracts were precipitated using acetone, trichloroacetic acid (TCA), and 20% (w/v) TCA/acetone and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. PWE was more or equally efficient for isolation of mistletoe proteins than evaluated conventional extraction methods. The proteomic analysis combining mass spectrometry and database searching confirmed the presence of 35 proteins in PWE extracts precipitated by acetone, which was the most compounds identified from all studied extracts. The PWE high extraction power was revealed for multiple viscotoxin isoforms and specific enzymes indispensable for the synthesis of terpenes.
Keywords: Lectin; Mass spectrometry; Pressurized water extraction; Protein; Sample preparation; Viscotoxin.
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