Method for obtaining peptides

Method of obtaining peptides from procaryotic and/or eucaryotic cells, said method comprising the following steps:

• a) lysis of the procaryotic and/or eucaryotic cells and recovery of the proteins thus obtained,
• b) denaturation of said proteins using at least one denaturing agent,
• c) alkylation of the denatured proteins using at least one alkylating agent,
• d) enzymatic proteolysis of the proteins obtained at the end of step c) using at least one proteolytic enzyme,
• e) recovery of the peptides obtained at the end of the enzymatic proteolysis step d), in which the lysis of the procaryotic and/or eucaryotic cells in step a) is lysis at a low concentration of chaotropic agent(s).