Protein Digestion Flashcards Preview

Biochemistry MBS > Protein Digestion > Flashcards

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

quality sources of protein

-animal proteins is of much higher percentage and is broken down much easier
-animal has complete amino acid sources
-chemical score for animal is high