as incubated for 40 min at room temperature shielded from light. Subsequently, prechilled acetone was added to the protein solution in a ratio of 6:1 and precipitated at −20 °C for 4 h. After centrifugation (10 000g, 4 °C) for 20 min, the precipitate was dissolved with 100 μL of 100 mM triethylammonium bicarbonate (TEAB). The processed protein samples were d