Flashcards in Lecture 19 - Digestion and Absorption of Protein Deck (23)
_________ are enzymes that need to be cleaved at one or more sites in order to become active/functioning.
__________ cleave proteins by hydrolyzing peptide bonds within the polypeptide chain.
_________ cleave AA from either N or C terminal ends of peptides or proteins.
Pepsin is produced by what organ?
Trypsin and chymotrypsin are produced by what organ?
Peptidases are produced by what organ?
What are two non-enzymatic components of gastric juice?
Gastrin acts on the _______ cells to secrete HCl.
Gastrin acts on the ________ cells to secrete pepsinogen.
HCl decreases pH to denature protein and provide a proper environment for _______.
Secretin and CCK are secreted in response to what?
Chyme moving through duodenum
Secretin stimulates the release of _________.
CCK stimulates the release of ___________ into the lumen of the small intestine.
Enteropeptidase catalyzes what reaction?
Conversion of trypsinogen to trypsin
What are the (2) products of protein digestion within the lumen of the small intestine?
35% neutral and basic AA
In the pathway of AA transport from the lumen of the SI to the portal blood, AA first go through the brush border where they are further hydrolyzed by _____.
Dipeptides and tripeptides are taken up by AA transporters using a _________ and then hydrolyzed by peptidases in intestinal cells.
Transport proteins (most are Na+ dependent) take AA through the _______ membrane, from the intestinal cell to the portal blood.
Enteropeptidases are found where?
Brush border of intestinal cells
If an AA can't be absorbed in the intestine, it also can't be absorbed in the ________ and is excreted.
Long-term use of proton pump inhibitors can result in _________________.
vitamin B12 deficiency
What are two enzymes that require B12 as a cofactor?
1. Methylmalonyl-CoA mutase (synthesizes succinyl-CoA in TCA cycle)
2. Methionine synthase