Method for the extraction of periplasmic proteins from prokaryotic microorganisms in the presence of arginine

A method for the extraction of a periplasmic protein of interest, which comprises the steps of:

• (i) culturing a Gram-negative bacterium transformed with an expression vector containing a gene coding for said protein of interest and means for a periplasmic expression thereof,
• (ii) subjecting the resulting culture to centrifugation or microfiltration thereby producing a cell pellet,
• (iii) lysing the cells from the cell pellet thereby obtained and centrifuging the resulting lysate thereby producing a pellet of cell debris,
• (iv) suspending the pellet of cell debris thereby obtained in a buffer solution containing arginine thereby producing a suspension,
• (v) centrifuging the resulting suspension thereby producing a supernatant, and
• (vi) recovering the protein of interest from the supernatant thereby obtained.