Topography of all tyrosine residues in subtilisin DY.

The extracellular alkaline proteinase subtilisin DY was nitrated with increasing amounts of tetranitromethane. At 2-fold molar excess of the reagent with respect to the tyrosine residues in the enzyme, when 1.3 residues were modified, a peak of the caseinolytic activity (13% increase) was observed. Evidence is provided that the diminishing of the pK of the… CONTINUE READING