Arginine-specific cysteine proteinase from Porphyromonas gingivalis as a convenient tool in protein chemistry

RgpB, a cysteine proteinase produced by Porphyromonas gingivalis, exhibits proteolytic activity selectively directed against peptide bonds containing an arginine residue in the P1 position. Here we show that this enzyme can b e used for very efficient and specific protein cleavage. RgpB is highly act ive even at high concentrations of denaturing agents, including urea (up to 6 m) and SDS (0.1 %), both of them being commonly used for solubilization of insoluble proteins and peptides. Moreover, RgpB is able to digest polype ptide chains in buffers supplemented with 1 % Triton X-100, 1 % octyl or de cylpyranoside, detergents employed for the enzymatic digestion of proteins transferred onto nitrocellulose membranes. These features render RgpB a sui table tool for use in protein chemistry.