lecture 13: Amino acid metabolism, transamination and deamination Flashcards
true or false: aamino acids are all considered esssential
false
we have essential and nonessential amino acids
what does it mean to be an essential amino acid
means it must be taken in through exogenous sources
give 3 examples of exogenous/essential amino acids
lysine/leusin
valine
tryptophan
what are 2 examples of non essential amono acids
alanine and glutamate (glutamic acid)
what is alanine
3 carbon structure ,very similar to pyruvate with a nh2 group added on
true or false: amino acids come from a carbohydrfate base
true
why is glutamic acid improtant
it will allow us to form amino acid pool
what are the plamsma proteins formed by liver
albumiin
fibrinogen
immunoglubulin
what does the liver create intterms of proteins
plasma proteins
what is albumin and its function
large plasma protein that is used to transport large free fatty acides to and from tissues
what is functinogen and its function
plasma protein that is a primary clotting agent in the blood
what is immunoglobulin
plasma protein important for immunie system
true or false: when the old plasma proteins die they get degrades and can non longer nbe used
false, they can be degreades and re used
what happens to the old plasma proteins once they are absorbed by the reticuloendtholial cells of spleen bone marrow etc
they are absorbed and borkem down and can re manufactured into new proteins
what are thr 4 bodies that can degreae aold plasma proteins
spleen
bone marror
connective tissue
lymph
what can the spleen due in terms of absorbing old plasma prpteins
removes old red blood cells and produced new ones
also important for antibody
what can the bone marrow due
create rbc
once a protein is broken down into amino acids does it rest in tiessues?
the amino acids dont rest in the tissie nut rather they go to the blood stream and they travel to the organ that needs it
true or false: skeletal muscle protein tissue can be broken down into amino acids that can then go to the liver and regorme new proteins
yes
know the reversility of prottein domains
lk
where does the degradation and formation of new proteins occur
reticuloendotthelial cells
what form do amino acids travel in
ionioned amino acids
what is the concentration of ionized amino acids in the plasma
35-65 mg/fl
true or false: after a meal with protein, it takes a long time for the aminos to leave plasms
false, plasma levels return to normal levels very rapdily but control is not known
where do the amino acids that anter the blood stream post prandial go
in msucle: forms new proteins
in lvier: makes plasma proteins
=reticululendoreticule cells form the new tisssue
is there storage for amino acids
no
they move thjrough circualtion to organs and tissues that are depleted of amino acid
when amino acid concreation decreases, what is done to compendate
cell protein catabolism compensates
breakdown bodies proteins to provide amino acids
true or false: aminos can go straight through lipid bilayer
false
how is traposnport of amino acids done
carrier mediated (need a protein trasnpored) throught faciliateted diffusion
there is a lot of free amino acids floating in the cell
false, there is not a lot of free aminos in the cell
why are tehree not alot of amino acids floating in the cell
they rapidly get tkaen up and used for proteins
how are proteins in diferent tissue cells linkes
via reversible exchauge with plamsma amino acids
true or false: plasma proteins are not a good srouce of amino acids and why
false
they can be degraded by tissue macroh[hages and release the amino acids
what are the 3 compoents you need to make non eseential amino acids
1) carbon skeleton
2) amino group
3) need an enzyme, aminotransferance
explain the carbon sketelon backbone needed for making non essential amino acids
you need alpha keto acid (ie glucose) that comes from carbs (like glycolysis, PPP, cirtric acid cycle intermediates)
what are some examples of carbon skeletons that can be used to make non essential amino acids
pyruvate, alpha ketoglutarate, oxaloacetate
explain the amino group part of making an amino acid
you need an amino group that can donate ints NH2 group to the carbon skeleton
what is the most common amino group used for making non essential aminos
glutamate/glutamiine
what is the amino trandfersage usually needed for making an amino
derivator of pyridoxine (vit. b6)
explain the example of forning glutamate
1) you got an NH2 and combine to make Nh4 fgroup from another amino acid
2) you have carbon skelteon (alpha keto which came from kreb cycle)
3) NADPH (from PPP) and NADH (from kreb) are oxidived
4) glutamate is formed
what is the definition of transamination
Transamination is the process by which amino groups are removed from amino acids and transferred to acceptor keto-acids
explain the process of making alanine (transamination)
1) Get pyruvate (carbon skeleton)
2) get glutamic acid (amino group)
3) Transamination occurs: NH2 from glutamic acid is donated to pyruvate to form alanine
4) oxygen that is lost from pyruvate goes to alpha ketoglutarte
5) alpha can go back into the kreb cycle to be borkem down
6) alanine can go back into circualtion and help with gluconeogenesis and can build up msucle proteins
what happens to the products of synthesis of alanine by transamination
1) left with alanine that can be a precursor for gluconeogenesis and can also be used for msucle protein synthesis
2) left with alpha ketoglutatrate which can then exnter the kreb cycle to be metabolized
what enzymes help accesralate the transamination of an essential aminion
aminotransferases
transaminases
what is deamination
the removled of an amine group (nh2) from a molucule.
what are the enxymes that catalize the deamination
deaminases
where is the majority of deamination taking place
in the liver (some in the kidney)
why would we go through a process of deamination
usefull to break down into amino acids when there is an excess of protein intake
=no storage for amino acids therefore liver will deaminate the excess amounts and break it down)
what does breaking down amino acids do
form an amino pool
when the amino group is removed from the amino acid what does it get converted to ?
ammonia
if there is an excess of glucatmate in the body
the liver will break it down and will take the nh4 group away and put it into the urine in kidney to form urea
explain deamination of glutamate in the body
1) Glutamate gets its NH4 group removed (by deaminanses=glutamate dehydrogenase)
2) this process requires NADP to be regued to NADPH
3) you are left with alpha ketoglutara which can then be used to synthessize atp in kreb cycle
4) the NH4 and Co2 formed from will go to the urea cycle and get converted to urea
when would deamination occur
increase in protein from meals
breaking down of protein in stavation periods
what is the difference between transmaination or deamination
trans: invovles synthesis of nonessential amino acids
deam: involved breakdown of non essential amino acids/breakdown of excess protein
true orfalse: transamination happens only in the liver
false, anywhere in the body
whree does deamination occur
only in the liver
what is the difference in enxymes between trans and deam
trans: transaminases/ aminotransferases catalyze
deams: deaminases
what is teh result of transamination
amino group goes to the keto group
what is the result of deamination
formation of ammonia
and elemenation of it through urea cycle
true or false: glutamic acid/glutate is the amino acid that goes through trans and deam the most
true, common for both
is transamination reversible
yes
is deamination reversiblr
no
what is the prupsoe of the glucose alanine cycle
maintain blood glucose levels
under what conditions is the glucose alanine cycle usually activatied and why
prolongued fasting or stavation
at this point you are breaking down a lot of protetins for energy source and left with excess amino acids
true or false: in starvation, your muscle only breaks down skelteal msucle
false, it also breaks down smooth and cardiac muscle to form an excess amino pool
explain the glucose alanine cycle
1) muscle protein breaks down causing an increase in amino acids
2) the amino acids are deaminated leaving you with excess NH4 stores
3) through a process an transamination you can form glutament in the muscle
4) glutatment will donate the NH2 group to pyruvate to form alanine (and aplha which goes to kreb)
5) alanine that is formed i nthe muscle does not remain there but leaves through circualtion and goes to lvier
6) once alanine enters the liver there will be a reverse reaction
7) Alanine will give its nh to alpha keto which formed glutate and oyruvate in excess (which goes to to glucose and is taken back to skelteal=gluconeogenesis )
8) Gluatmeate is deaminated to form ammoinium which is released through urea
true or false: during dttarvation we only use fat stored
false
we use fat sotres (which can cause ketone bodies)
we used glycogen stores (which will be depleted fast)
we use amino acids
what happens to tthe ammonia made from the breakdown of glutamate
can go towarde generating more amino acids or it can be extrecreuted via urea
how can ammonia because excreted
main throough urea (2 ammounia and carbon idioxide )
where does urea formaation ofccur
mainly in the lvier
what are the ammoinia carriers of the urea cycle
ornithine citrulline arginine
true or false: tthe urea cycle is not linked to the kreb cycle
false
is ammonia ttoxic tto he body
yes, theat is why we excrete it as much as bpossible)
why is excess free NH4 toxic
depletes alpha ketto glutaratet which will stop the kreb cycle
where does amino acid degradeation mostly happen
in the liver
what is tthe fucntion of breaking down amino acids in the liver
to form major metabolic intermiedates can be be converted into glucose or oxidixed by the kreb cycle
amino acids that are degreaded to form acetyl coa or acetoacetyl coa are called… and why
ketogenic amino acids because they give rise to ketone bodies
amino acids tthat are degraded and form glucose or go through kreb cycle are called … and why
glucogenic because the gorm glucose
making ketone bodies from anino acids is only bad
faalse
it can be used for metabolism
whaat arae some examples of ketogenic amino acids
leusine
lysin
tryptophna
because htey are forming acetyl coa=ketone bodies
what are some examples of glucogenic amino acids
glutamine
proline
arginine
glucogenic amino acids from precors for..
glucose
ketogenic amono acids form precoursed
for ketone bodies
what process are ketogenic amino acids important force
ketogenesis
what process are glucogenic amino acids importatnt for
gluconeogenesis
glucogenic amino acids are comprised of …
most essential and non essential amino acids
ketogenic amonos include exclsuively
leucine and lysine
what hormones increase protein synthesis
growth homrone
insulin
testosterone
thryoxine sometimes
explain grouth hormones affect on protein
increases protein synthesis
unsure what mecanism ,guess is to increased AA transprot
explain insulin effect on protein
increases protein syntheisis
unknpwn ,AA transprot
explain cortisol/glucocorticorids effect on protein
causes protein breakdown
breakdowb of extraheptatic tissue proteins
explain testosterone
increases protetin synthesis
explain thyroxine effect on protein
no directi effect
if CHO are depleted: increased proteolysis, icnrease metabolism
If CHO are adequate: increased protein synthesis
