Lecture 29-30 Flashcards
do plants use amino cids for energy
no
how do plants get nitrogen
nitrogen fixing bacteria (N2 to NH3)
where does degradation occur of dietary proteins
gastrointestinal tract
hormone secreted when dietary protein enters the stomach
gastrin
what does gastrin stimulate the release of
HCl and pepsinogen
zymogen that is converted to active pepsin by autocatalytic cleavage at low pH
pepsinogen
cleaves long polypeptide chains into a mixture of smaller peptides
pepsin
hormone secreted into the blood in response to low pH in the small intestine
secretin
where is secretin secreted
into the blood
what does secretin stimulate
pancreas to secrete carbonate into the small intestine
hormone secreted into the blood in response to the arrival of peptides in the duodenum
choleccystokinin
zymogens are secreted by what
exocrine cells of the pancreas
what does cholecystokinin stimulate secretion of
trypsinogen, chymotrypsinogen, procarboxypeptidase A and B
zymogen of trypsin
trypsinogen
zymogen of chymotrypsin
chymotrypsinogen
zymogen of carboxpeptidases A and B
procarbboxypeptidases A and B
proteolytic enzyme that converts trypsinogen to trypsin
enteropeptidase
eteropeptidase converts what to what
trypsinogen to trypsin
activates additional trypsinogen, chymotrypsinogen, procarboxypeptidase, and proelastase
trypsin
protein inhibitor that further protects the pancreas against self digestion
pancreatic trypsin inhibitor
what is the first thing to break down proteins
pepsin
what is used as a marker for protein degradation
ubiquitin
what are proteins degraded by
28S proteasome
what is structure of 26S
hollow
ubiquitin protein enters where
26S core,
what happens to protein in 26S core
is broken to free amino acids
what are the free amino acids made during protein degradation used for
new proteins
wehre does most of amino acid catabolism and syn take place
liver
what amino acids enter liver
ones you consume (via blood vessels)
why can’t ammonia be transported in blood
increase in blood pH
due to not being able to transport ammonia, what does this mean
we cannot just deaminate Amino acids
how is NH4 transported safely
certain amino acids
first step of transporting NH4
transamination
what is the accepting amino acid for NH4
alpha ketoglutarate
what is cofactor for transamination
vitamin b6
transfer alpha amino group to a carbon atom of alpha
transamination rxn
catalyze the removal of the alpha amino groups
aminotransferases
are transamination reactions irreversible or reversible
reversible
what does ammonia compete with
K+
why does ammonia compete with K+
for transport into astrocyte cells
1 urea molecule = what
2 molecules of nitrogen
what accepts an amino group
PLP (aldehyde form)
donates its amino group to an alpha keto acid
pyridoxamine phosphate (aminated form)
what does Nh4 and K+ competition result in
elevated extracellular (K+)
symporter that transports Na, K. Cl
Na2+-K+-2Cl- cotransporter 1 (NKCC1)
excess Cl- from the excess K+ alters what
neuronal response to the neurotransmitter GABA
what transports N from muscle to liver
alanine
what else can be used to transport N
glutamine
how is glutamine made
glutamine synthesis, requires ATP
organism that excretes N2 in the form of ammonia
ammonotelic
organism that excretes urea
ureotelic
organism that excretes uric acid
uricotelic
what are the ammonotelic animals
most aquatic vertebrates
uricotelic anomals
birds, reptiles
ureotelic animals
many terrestrial vertebrates, also sharks
glutamate releases its amino group as
ammonia in the liver
NH4+ in the mitochondria comes form many different alpha amino acids in the form of -
amino group of l-glutamate, amide nitrogen of glutamine
pathway by which alanine carries ammonia and the carbon skeleton from pyruvate to liver
glucose alanine cycle
catalyzes the oxidative deamincation of glutamate to produce NH4+ and alpha ketoglutarate
l-glutamate dehydrogenase
where is l-glutamate dehydrogenase present
mitochondrial matrix
alpha ketoglutartate product can be…
oxidized as fuel, or serve as a glucose precursor in gluconeogenesis
glutamate dehydrogenase is positively modulated by..
ADP (signals low glucose levels)
glutamate dehydrogenase dehydrogenase is negatively modulated by..
GTP (signals high levels of alpha ketoglutarate)
skeletal muscles produce what
pyruvate, lactate ammonia
interconverts pyruvate and alanine via transamination with glutamate
allanine aminotransferase
interconverts pyruvate and alanine via transamination with glutamate
alanine aminotransferase
catalyzes combination of free ammonia with glutamate to yield glutamine
glutamate synthetase
critical to transport toxic ammonia to liver
glutamine synthetase
does glutamine synthetase require ATP
yes
glutaminase
catalyzes conversion of glutamine to glutamate and NH4+
used to syn other N containing compounds, transport N from extra haptic tissues to liver
glutamine
is glutamine regulated
yes, highly
glutamine synthetase is active when
deadenylylated
glutamine synthetase inactive when
adenylylated
is AMP on active or inactive version of glutamine synthetase
inactive
glutamine synthetase converts what to what
glutamate to glutamine
product of glutamine are…
inhibitors of glutamine snthetase
adding AMP
adenylation
glutamate dehydrogenase deaminates what to what
Glutamate to alpha keto gluturate
glutaaminase deaminates what to what
glutamine to glutamate
how is uridylylation regulated
allosteric regulation
where does urea cycle take place
cytosol and mitochondria
bicarbonate activated by phosphorylation , what enzyme
carbamoyl phosphate synthetase 1
what does carbamoyl phosphate synthetase 1 switch
swaps phosphate for ammonia
does Carbamoyl phosphate synthetase 1 use ATP
yes
how many ATP is required to make a carbamoyl phosphate
2
urea cycle step 1
ornithine + carbamoyl phosphate -> citruline
urea cycle step 1 enzyme
ornithine transcarbamoylase
urea cycle step 2
citruline -> argininosuccinate
enzyme for step 2
argininosuccinate synthetase
two cofactors of step 2
ATP + aspartate -> PPi + AMP
urea cycle step 3
argininosuccinate -> arginine
what leaves in step 3
fumarate
step 3 enzyme
argininosuccinase
step 4
arginine -> ornithine
enzyme step 4
arginase
what’s used and released in step 4
h2o in, urea out
how many amino groups = 1 urea
2
how many ATP are used for urea cycle
2 atp (+2ATP for carbamoyl phosphate)
what is the 1 thing you get from urea cycle
1 fumarate
what can fumarate be converted to
malate
what can be used to form malate
fumarate
functions to regenerate NADH in the mitochondria
malate aspartate shuttle
2 ways urea cycle is regulated
level of enzyme synthesis, allosteric regulation of carbamoyl phosphate synthetase 1
catalyzes formation of N-acetyl glutamate from acetyl CoA and glutamate
N-acetylglutamate synthase
allosterically activates carbamoyl phosphate synthetase 1
n-acetylglutamate
too much protein = what
buildup of nitrogen in body
essentail amino acids are what
amino acids that cannot be synthesized by humans and must be obtained in the diet
albinism defective enzyme
tyrosine 3-monooxygenase (tyrosinase)
carbamoyl phosphate synthetase 1 deficiency defective enzyme
carbamoyl phosphate synthetase 1
maple syrup urine disease other name
branched chain ketoaciduria
maple syrup urine disease enzyme
branched chain alpha keto acid dehydrogenase complex
phenylkeoturia defective enzyme
phenylalanine hydroxylase
tyrosin 3-monooxygenase medical conditon
albinism
carbamoyl phosphate synthetase 1 medical condition
carbamoyl phosphate synthetase 1 deficiency
branched chain alpha keto acid dehydrogenase complex medical condition
maple syrup urine disease
phenylalanine hydroxylase medical condition
phenylketonuria
if issue with urea cycle enzymes, can treat with what
benzoate and/or phenylbutyrate
valine, leucine, isoleucine go to alpha keto acids
male syrup urine disease
3 amino acids involved in maple syrup urine disease
leucine, isoleucine, valine
what is inhibited in maple syrup urine disease
branch chain alpha keto acid dehydrogenase complex
what can maple syrup urine disease cause
mental degradation
in phenylketonuria, what can’t be made
tyrosine
what enzyme does PKU block
phenylalanine hydroxylase
what does phenylalanine hydroxylase normally do
phenylalanine to tyrosine
PKU results in what
accumulation of keto acids
PKU makes what an essential amino acids
tyrosine, bc its production is blocked
dipeptide absorbed and broken down to phenylalanine and something else
aspartane
what can plants do that we can’t do (amino acids)
they can put N groups on C skeletons to form amino acids
lightning and UV makes up what percent of Nitrogen cycle
15%
industrial makes up what percent of nitrogen cycle
25%
microorganisms make up what percent of nitrogen cycle
60%
nitrogen fixation main enzyme
dinitrogenase
most abundant gas in our atmosphere
molecular nitrogen
electrons in nitrogen fixation
extensive e transfer
how many ATP required per N2
16
involves extensive transfer of e- eventually transferred
nitrogen fixation
in amino acid synthesis, what is made first
carbon skeleton
in amino acid synthesis, what happens second
transamination reaction to add amino group
animals cannot synthesize what
EAA
how many biosynthetic families are there
6
when we synthesize AA, we use what as donors
glutamate and glutamine
2 universal AA donors
glutamate and glutamine
key in degradation and AA syn
transamination
remove amino group from 1 AA to a keto acid, forms new AA
transamination
