PURIFICATION AND CHARACTERIZATION OF A SERINE PROTEINASE FROM SENESCENT SPOROPHORES OF THE COMMERCIAL MUSHROOM AGARICUS-BISPORUS

A proteinase has been purified from the stipes of senescent sporophore s of the mushroom Agaricus bisporus. The proteinase was inhibited by P MSF. It has a broad pH optimum, 6.5-11.5, and a narrow substrate speci ficity, requiring both a hydrophobic amino acid in the P1 position and a minimum peptide chain length. The apparent molecular mass of the pr oteinase was 27 kDa when determined by SDS-PAGE and 14.1 kDa when meas ured by gel filtration. The isoelectric point of the proteinase was 9- 0. Polyclonal antibodies have been raised to the proteinase. The prote inase from A. bisporus has similar properties to, and 60 % N-terminal sequence identity with, proteinase K from the fungus Tritirachium albu m.