Method and device for protein preparation

A method of preparing a sample comprising one or more proteins of interest, the method comprising the ordered steps of:

• providing a sample comprising a population of proteins of interest solubilised with a surfactant in a medium;
• exposing said sample to a mild precipitant to cause precipitation of said proteins;
• wherein the mild precipitant causes the protein solubilised with surfactant to precipitate to form a suspension of particles of protein, wherein said particles of protein are sensitive to protease digestion;
• during or after the precipitation step, bringing said sample into contact with a matrix that is a depth filter adapted to capture said precipitated protein particles and prevent excessive aggregation of precipitated protein particles to thereby allow a protease to digest the protein particles in situ;
• washing the matrix containing the captured precipitated protein particles to remove the surfactant;
• and
• after washing the matrix, digesting the protein particles in situ.

A method of preparing a sample comprising one or more proteins of interest, the method comprising the ordered steps of:

• providing a sample comprising a population of proteins of interest solubilised with a surfactant in a medium;
• exposing said sample to a precipitant, wherein said precipitant solubilises the surfactant, causes precipitation of said proteins as a suspension of particles of protein, and does not render the precipitated proteins insensitive to protease digestion;
• during or after the precipitation step,
• bringing said sample into contact with a matrix that is a depth filter having a network of pore channels adapted to capture said precipitated protein particles throughout the depth filter and thereby prevent excessive aggregation of precipitated protein particles at a surface of initial contact between the precipitated protein particles and the depth filter, and
• wherein further said matrix does not bind the solubilised surfactant;
• and
• digesting the captured precipitated protein particles in situ using a protease.