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?  Chymotrypsin is a digestive protease involved in breakdown of proteins and peptides so that their amino acids can be used.?  It is synthesized in the pancreas of mammals and released intothe digestive tract.?  Originally synthesized as a 245 residue protein, chymotrypsinogen.Activation? Chymotrypsin becomes activated after the proteolysis of chymotrypsinogen.? Activation of chymotrypsin is achieved by “clips” in its polypeptide chain, so active chymotrypsin consists of three distinct chains. These remain bound together in a single domain, covalently held together by disulfide bonds.? The activity of chymotrypsin is regulated by controlling when the “clips” are made.? Dipeptides 14-15 and 147-148 are clipped out, transforming the protein into active chymotrypsin.? Therefore it has 3 chains but these are covalently linked by disulfide bridges.ENZYME NOMENCLATURE? The EC number of chymotrypsin is  The number 3 represents hydrolase?  The number 4 represents peptidase nature of enzyme?  The number 21 represents serine endopeptidases?  The number 1 represents chymotrypsin?  The gene ID number is 11330PRIMARY STRUCTURE?  The primary structure shows that disulfide bonds are the crucial role to the protein folding.?  The protein is spherical and itself consists of three polypeptide chains.?  There is also a pocket in the protein which is known as the active site.THE ACTIVE SITE?  The active site includes thecatalytic triad1.  Ser-195,2.  His-57, and3.  Asp-102?  Ser-195 is hydrogen bonded to the His-57 and it in turn is hydrogen bonded to the Asp-102 residue.?   The His-57 role is to position the serine residue and polarize the hydroxyl group so it can be deprotonated to the alkoxide ion.?  In the presence of the substrate, this accepts a proton by acting as a base.?  Asp-102 orients the His-57 and stabilizes it throughhydrogen bonding and electrostatics.3D STRUCTURE OF CHYMOTRYPSIN?  Globular single- domain protein.SITE SPECIFIC?  Chymotrypsin is a site specific and will only cleave the carboxyl side of large hydrophobic or aromatic amino acids unless the next amino acid is proline (Pro)?  Chymotrypsin selectively cleaves peptide bonds formed by aromatic amino acid residues.?  It uses an active serine residue to perform hydrolysis on the C-terminus of the aromatic amino acids of other proteins. Chymotrypsin is a protease enzyme that cleaves on the C-terminal tyrosine (Y), phenylalanine (F) and tryptophan (W) on peptide chains.CHEMICAL PARAMETERSCATH Classification?  Class: Mainly Beta?  Architecture: Beta Barrel?  Topology: Trypsin-like Serine Protease?  Accession: 4H4F_A?  Number of amino acids: 249?  Formula: C1244H1911N365O355S11?  Molecular weight: 28012.75?  Theoretical pI: 7.36?  pH: 7.8-8.0?  Total number of atoms: 3886AMINO ACID SEQUENCETotal number of negatively charged residues (Asp + Glu): 25Total number of positively charged residues (Arg + Lys): 25Estimated half-life:? The N-terminal of the sequence considered is V (Val).? The estimated half-life is:? 100 hours (mammalian reticulocytes, in vitro).? >20 hours (yeast, in vivo).? >10 hours (Escherichia coli, in vivo).Active Site Residues:?  Histidine (H57)? Aspartate (D102)?  Serine (S195)Instability index:?  The instability index (II) is computed to be 26.43 This classifies the protein as stable.Aliphatic index: 84.50Grand average of hydropathicity (GRAVY): -0.343IMPORTANCE?  Aid in digestion.?  Treat inflammation and reduce swelling (i.e., soft tissue injuries, acute traumatic injuries, sprains, contusions, hematomas, ecchymoses, infections, edema of the eyelids and genitalia, muscle cramps, and sports injuries).?  Treat arthritis and such other autoimmune diseases as lupus, scleroderma, and multiple sclerosis.?  Treat ulcerations and abscesses.?  Treat enterozoic worms and other parasites in the digestive tract.?  Treat cancer (a controversial use that requires much more scientific study, though chymotrypsin may be helpful in alleviating effects of radiation treatment or chemotherapy).?  Treat shingles and acne.?  Decrease effects of sun damage and age spots.APPLICATIONS:?  Sequence analysis?  Peptide synthesis?  Peptide mapping?  Peptide fingerprinting

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