<prompt> A common feature of all serine proteases is:Autocatalytic activitation of zymogen precursorTight binding of pancreatic trypsin inhibitorCleavage of protein on the carboxyl site of serine residuesPresence of Ser-His_Asp catalytic triad at the active site  <response>: Serine proteases are a group of powerful enzymes that cut peptide bonds of few proteins. They help in digestion, immunity, clotting and also aid in sperm entering the egg. The active site of serine proteases contain three amino acids serine, histidine and aspaate together referred as the catalytic triad. Ref: Textbook of Biochemistry By DM Vasudevan, 3rd Edition, Page 35 