Flashcards in Protein Digestion Deck (38):
1
sources of amino acids
-body protein (major source)
-dietary protein
-digestive enzymes
2
uses for amino acids
-synth of nitrogen containing compounds
-degradation for energy to make glucose
-protein synth
-poop production
3
what concentration are amino acids maintained at in the blood
-high for use all over the body
4
two sources of blood protein
-3/4 body breakdown
-1/4 dietary
5
dietary protein digestion
-glands of the stomach secrete acid and pepsinogen
-acid denatures proteins and pepsin produces peptides
-peptides eneter the small intestine, pancreas secretes bicarb and zymogens
-activated enzymes in the duodenum digest long peptides into short ones
-enzymes of intestinal lumen and villi produce mostly amino acid for absorption
6
pepsinogen
-is not active at neutral ph
-at higher ph, a pro-peptide is blocking the active site
-at lower ph, autoactivtion happen and the site is exposed
7
regulation of digestion in the small intestine
-acid chyme passes to duodenum
-mucosal cells release of secretin and CCK into the blood
-gall bladder contracts and pancreas releases juices
8
what does the pancreas secrete
-bicarb
-inactive zymogens (these are activated by enzymes from the duodenum)
9
trypsinogen
-activated by enteropeptidase which starts off the process of digestion. made into trypsin
-trypsin acts on trypsinogen to turn it into trypsin
-activates chymotrypsinogen, proelastase, and procarboxypeptidase
10
degradation of digestive enzymes
-they degrade themselves as they run out of dietary amino acids to work on
-degradation = production (70g/day)
11
uninhibited trypsin in pancreatic cells
-leads to pancreatitis
-could be from a mutation
-
12
carboxypeptidase produces
mostly amino acids
13
aminopeptidases and dipeptidases produce
amino acids
14
absorption uptake in and out of cells occurs via
-transporters
-there is a high aa concentration in cells so you must use energy to move amino acids in,
-you can just use facilitated transport to move amino acids out
15
where does amino acid transport occur
-intestines from the lumen
-refiltered from urine in the kidney for reuse
-across mitochondrial membranes
-solute carrier transporters are a diverse group
16
characterization of amino acid transporters
-often sodium linked transporters that use energy to pump sodium out of the cell in order to establish a sodium gradient that is used to pump the amino acids in (NA/K ATPase)
-one transporter will carry many aa's that have similar characteristics
17
where is the first place amino acids go
-liver via portal vein
18
defective kidney transport for cystine
-can cause cystinuria
-carrier rate of 1:50
-resorption rate rises
-results in high cystein in urin and it is of limiited solubility so it results in stones
-also high lysine
19
niacin (VB3)
-pellagra
-hartnip
-made from tryptophan
-deficiency disease, pllagra causes its victims to experience dermatitis, dirrhea, and dementia
-clinical features of hartnup disease are nearly identical to thos of pellagra, although more intermittent and slightly less than pellagra
20
hartnup disease
-abnormal excretion of tryptophan into the urine and deficient in absorption in the intestine
-patient is characterized by intermittent attacks of dermatitis, diarrhea, and dementia
-tryptophan can be converted into niacin, a precursor to NAD
-affects occur in the brin and skin
21
cathepsins
-lysosomal proteases
-effective for degrading extracellular proteins
22
sources for amino acids from protein degradation oustide of dietary proteins
-lysosomal system (cathesins)
-digestive enzyme turnover
-the ubiquitin/proteasome pathway (UPP): major pathway for degradation of intracellular proteins (muscle)
23
degradation rate of proteins
-varies
-proteins that shouldnt be around for a long time such as cell cycle proteins will degrade more quickly
24
what happens to proteins that are destine for the ubiquitin pathway
-enzymes E1,2, and 3 add ubiquitin to the target which tags it for degradation
-final product is polyubiquitinated
25
the proteasome
-present in the cytoplasm
-composed of two regulatory particles and a core particle an
-end product is amino acids
-processing is upregulated when needed
26
regulatory particle
-selects substrates
-remoives Ub for recycling
-edits wrongly tagged proteins
27
core particle
-this is where proteins are digested into peptides of 7 to 10 aa's
28
ubiquitin signals in the protein sequence and not variable
-N end rule: methionine is the slowest
-PEST sequence
-destruction boxes
29
ubitquitin signals that are external and variable
-phosphoryltaion
-denaturation/damage
-facilitators/chaperons
30
HPV E6
-faciliates the degradation of p53
-this protein forma complex with its target and makes it more likely to be ubiquinylated
-this is a viral protein which upregulates the cell cycle by degrading p53, a powerful tumor supressor
-certain forms of the virus are assoicated with cervical cancer
31
parkinsons
-lewy bodies (protein deposits in the brain)
-causes a loss of neurons, dopamine
-L dopa is the most common treatment
32
parkin and E6AP
-examples od E3 type ubitquitin ligases that are associated with parkinsons and HPV induced disease
33
plasma
-this is how proteins are transported in the blood
-alanine and glutamine are in the highest concentration due to the way they are metabolized
34
free amino acids
levels are low compared to that of polymerized aa's
-95% is turned over every ten mins
35
essential amino acids
-must be obtained from the fiet
-if something is too hard to make, we eat it
-
36
list the essential amino acids
-arg
-val
-phe
-his
-thr
-met
-iso
-lys
-leu
-tryp
-are valuable phor his thriving metabolism in lyfes leunatic tryp
37
inadequate protein in the diet
-kwashiorkor
-marasmus
-bloated stomachs due to loss of plasma protein and fatty liver
38