First, to talk about the structure of trypsin, the structure of trypsinogen must be discussed. Trypsin is secreted in its inactive form, trypsinogen, and to activate it a small portion of the peptide must be cleaved. Trypsinogen is 245 amino acids
long. Trypsin is an enzyme integral to the cleavage of protein bonds for digestive systems. As part of the Serine Proteases family, Trypsin contains an integral Ser (Ser-195) in the active site. However, the Ser is only one of three residues constituting the catalytic triad which also houses a His and Asp residue. The three interact in such a way to cleave protein bonds.
For peptide bond cleavage, the active site receives a peptide into the active site that then is attacked by a lone pair on the nearby serine. Hydrogen bonding then stabilizes the bond protein as the proteins nitrogenous end is protonated to create a positively charged leaving group. As the nitrogen leaving group exits, the oxyanion reduces to a carbonyl at the same time as the leaving group attacks a proton. A nucleophilic water then attacks the newly formed carbonyl compound again forming a oxyanion. The now attached water molecule then loses a proton to form a hydroxyl group before donating a bond to a hydroxyl leaving group and forming a new carboxylic acid. The protein is thus restored to its original state as the final protons are transferred.
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| 3cin, resolution 1.70Å ()
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| Ligands:
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, ,
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| Gene:
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TM1419, TM_1419 (Thermotoga maritima MSB8)
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| Activity:
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Inositol-3-phosphate synthase, with EC number 5.5.1.4
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| Resources:
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FirstGlance, OCA, RCSB, PDBsum, TOPSAN
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| Coordinates:
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save as pdb, mmCIF, xml
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Ann Taylor