Graspases--a special group of serine proteases of the chymotrypsin family that has lost a conserved active site disulfide bond.

摘要: In this report we propose a new approach to classification of serine proteases the chymotrypsin family. Comparative structure–function analysis has revealed two main groups proteases: group trypsin-like enzymes and graspases (granule-associated proteases). The most important structural peculiarity is absence conservative “active site” disulfide bond Cys191–Cys220. residue at position 226 in S1-subsite responsible for substrate specificity, whereas crucial specificity classical located 189. We distinguish three types on base their specificity: 1) chymozymes prefer uncharged substrates contain an 226; 2) duozymes possess dual chymotrypsin-like Asp or Glu 3) aspartases hydrolyze Asp-containing Arg 226. correctness proposed was confirmed by phylogenic analysis.