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Chymotrypsin quiz #1 Flashcards

Chymotrypsin quiz #1
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  • What is the function of chymotrypsin in protein digestion, and which amino acid residues does it preferentially cleave?
    Chymotrypsin is a peptidase secreted by the pancreas that breaks down dietary proteins by cleaving peptide bonds at the C-terminal side of aromatic amino acids, specifically phenylalanine, tyrosine, and tryptophan.
  • Describe the role of the catalytic triad in chymotrypsin's active site and explain how these residues contribute to its enzymatic activity.
    The catalytic triad in chymotrypsin's active site consists of aspartate 102, histidine 57, and serine 195. Aspartate 102 positions histidine 57 to act as a base, which then accepts a proton from serine 195, increasing serine's nucleophilicity and enabling it to attack peptide bonds during catalysis.
  • What is the primary function of chymotrypsin in the digestive system?
    Chymotrypsin breaks down dietary proteins by cleaving peptide bonds, aiding in protein digestion and amino acid absorption.
  • Which organ secretes chymotrypsin, and in what form is it initially released?
    The pancreas secretes chymotrypsin in its inactive zymogen form called chymotrypsinogen.
  • At which specific sites does chymotrypsin preferentially cleave peptide bonds?
    Chymotrypsin preferentially cleaves peptide bonds at the C-terminal side of aromatic amino acids such as phenylalanine, tyrosine, and tryptophan.
  • What is the catalytic triad in chymotrypsin's active site composed of?
    The catalytic triad consists of aspartate 102, histidine 57, and serine 195.
  • How does histidine 57 contribute to chymotrypsin's catalytic mechanism?
    Histidine 57 acts as a base, accepting a proton from serine 195, which increases serine's nucleophilicity for peptide bond cleavage.
  • What role does aspartate 102 play in the catalytic triad of chymotrypsin?
    Aspartate 102 positions histidine 57 to act as a better base, enabling it to accept a proton from serine 195.
  • Why is serine 195 important in chymotrypsin's enzymatic activity?
    Serine 195 acts as the nucleophile that attacks the peptide bond, initiating the cleavage of the substrate protein.
  • What would happen to chymotrypsin's activity if any one of the catalytic triad residues were removed?
    Chymotrypsin's catalytic activity would be lost if any one of the three residues (aspartate, histidine, or serine) were removed.