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25 Cards in this Set

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what molecules cause the hydrolysis of peptide linkages anywhere within the protein chain?
endopeptidases
what molecules cause the hydrolysis of peptide linkages at the carboxy and amino terminal ends?
exopeptidases (amino- and carboxy-peptidases)
where does the digestion of proteins begin?
in the stomach
Hydrochloric acid is produced by the ______ cells of the ______ mucosa.
parietal, gastric
Hydrogen atoms autoactivate this stomach protease. and at what pH does its activation become autocatalytic?
pepsinogen -> Pepsin (active)

pH: 4.6
what is the optimal pH for pepsin?
1.5-2.5
peptide bonds of which amino acids in a protein or polypeptide chain do pepsin hydrolyze?
Tyrosine, phenylalanine
when food leaves the stomach it is in a semi-liquid state called,___.
chyme
through what do the pancreatic juices involved in protein digestion travel to get to the small intestine?
pancreatic duct
what is the pH of pancreatic juice? what ion serves to neutralize the acidic chyme?
pH of 7-8. bicarbonate (HCO3-)
what are zymogens?
inactive, proteolytic precoursors to proteases.
what are the means by which stomach pepsinogen can be activated to pepsin?
by H+ ions, a pH of 4.6, and by other pepsin molecules.
what are the Endopeptidases produced by the pancreas?
Trypsinogen, chymotrypsinogen, and proelastase.
by what is trypsinogen activated?
enterokinase and other trypsin molecules
by what is chymotrypsinogen activated?
trypsin
by what is proelastase activated?
trypsin
what are the exopeptidases produced by the pancreas?
procarboxypeptidase A and B
by what molecule are procarboxypeptidase A and B activated?
trypsin
what is the specificity of trypsin?
crboxyl side of lysine and arginine
what is the specificity of chymotrypsin?
crboxyl side of Phe, Tyr and Trp (aromatic amino acids)
what is the specificity of elastase?
elastin...
what are the specificities of carboxypeptidases A and B?
A: C-terminal amino acid, val, leu, ile, and ala. (hydrophobic amino acids)
B: C-terminal amino acid, lys and arg
what hormone initiates the secretion of HCO3- in the small intestine?
Secretin
what hormone initiates the secretion of HCl and pepsinogen in the stomach?
Gastrin
where are the zymogens of the pancreas activated? (pancreas or small intestine)
small intestine