Serine proteinase activity was assayed during sporophore
maturation and postharvest senescence in Agaricus bisporus.
Serine proteinase accumulated largely in stipe tissue early during
postharvest storage and in the later stages of maturation of unpicked
sporophores. Western blot staining correlated with enzyme activity
indicating de novo synthesis. The enzyme could not be
detected by Western blotting in freshly harvested sporophores at an
early maturation stage. Small increases in activity were detected in
the cap tissue during the final stages of senescence, postharvest and
in unpicked sporophores. The distribution of the serine proteinase in
senescent sporophore tissues (high in stipe, low in cap) was confirmed
by histochemical and immunologically stained tissue prints.