title: Maleylation and pH-dependence of Streptomyces griseus protease B.
abstract: The enzymatic activity of Streptomyces griseus protease B (SGPB) was measured over pH range 8.4--11.5 using a specific new, chromophoric substrate N-succinyl-glycyl-glycyl-L-phenylalanine p-nitroanilide. It was found that the activity is dependent on ionization of a single group with apparent pK = 10.84, possibly lysine-125. Maleylation of the epsilon-amino group of this lysine was linearily associated with the loss of enzymatic activity. It is therefore suggested that the electrostatic interaction between the side chain of lysine-125 and the alpha-carboxyl group of the C-terminal tyrosine is crucial to the active conformation of the enzyme. In contrast the maleylation of the alpha-amino group of the N-terminal isoleucine was rapid but could not be correlated to the loss of activity.
mesh_terms: D005663:Furans; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007532:Isoleucine; D008239:Lysine; D008299:Maleic Anhydrides; D010447:Peptide Hydrolases; D011487:Protein Conformation; D013305:Streptomyces griseus / Q000201:enzymology*; D013329:Structure-Activity Relationship
chemical_list: D005663:Furans; D008299:Maleic Anhydrides; D007532:Isoleucine; D010447:Peptide Hydrolases; D008239:Lysine