Lec 5 - Nitrogen Metabolism Flashcards
there are blank aa that are essential from diet
10
the body cannot store this
protein
essential aa mnemonic
pvt tim hall
pvt tim hall
phenylalanine, valine, threonine, tryptophan, isoleucine, methionine, histidine, arginine, leucine, lysine
a child is in blank nitrogen balance which allows for blank
positive, growth
a normal adult is in blank nitrogen balance
equal
not enough nitrogen in our diet causes blank nitrogen balance
negative
average man needs blank grams of nitrogen per kg of body weight
.8
appears in the weaned child who was nourished with an adequate caloric diet but deficient in protein and characterized by hair changes, skin disorders, hepatomegaly
kwashiorkor
deficiency of both protein and calories characterized by wasting away of subcutaneous fat and muscles and lack of growth and development
marasmus
putting a protein in an acidic environment causes this
denaturation
pepsinogen makes pepsin which is an enzyme with specificity for these
Phe, Tyr, Trp, Leu
intracellular protein degradation that requires energy
atp dependent proteolysis
intracellular protein degradation that does not require energy
atp independent proteolysis
atp independent proteolysis uses these
extracellular proteins, lysosomes, cathepsins
atp dependent proteolysis uses these
intracellular proteins
E1 is the blank enzyme atp dependent proteases
activating
E2 is the blank enzyme atp dependent proteases
conjugating
E3 is the blank enzyme in atp dependent proteases
ubiquitin protein ligase
the only essential fatty acids in diet
omega 3, omega 6
we get nitrogen from the blank we take in
aa (amine nitrogen)
major end product of amino nitrogen metabolism in body
urea
less numerous things in urine
ammonia, creatinine, uric acid
uric acid is the end product of blank
purine metabolism
two aa that are semi essential
histidine, arginine
pepsin, trypsin, elastase, chymotrypsins are all blank so they are not activated until they leave their cell of origin
zymogens
brush border cells of SI release blank
enteropeptiase
enteropeptidase converts blank to blank
trypsinogen, trypsin
atp dependent proteolysis occurs in blank and targeting of a protein to proteosomes requires blank
pretoasomes, ubiquitin
atp independent proteolysis occurs in blank by proteases called blank
lysosomes, cathepsins
caspace and calpains are proteolytic enzymes involved in blank
apoptosis
group specific transporters for aa
small neutral, large neutral, basic, acidic, proline/glycine
three ways to transport aa
glutamyl cycle, group specific, facilitated
facilitated transport is blank transport
secondary active transport
aa transport that has been seen in brain, intestine and kidney
glutamyl cycle
blank is required for optimal activity of glutamyl transferase
sodium
all aa except these two can participate in transamination reacts
threonine, lysine
most nitrogen of aa appears in the form of blank due to action of transaminases
glutamate
glutamate is subject to oxidative deamination by blank
glutamate dehydrogenase
transaminases have an equilibrium near blank which is an advantage
1
two most common transaminases
aspartate aminotransferase (GOT), alanine aminotransferase (GPT)
cofactor involved in many enzyme catalyzed transformations of aa
pyridoxal phosphate
disposing amino group from aa can be via blank or blank deamination
oxidative, non oxidative
non oxidative deamination enzymes require blank
PLP pyridoxal phosphate
L amino acid oxidase catalyzes reactions with L aa except these two
serine, threonine
d amino acid oxidase is in the liver and kidney and is blank because it can be in glycine metabolism or metabolize d aa from bacterial cell walls
enigmatic
A group of pyridoxal phosphate dependent dehydratases catalyze the removal of the amino groups of serine, threonine, cysteine and histidine to form keto acids and NH3.
nonoxidative deamination
this enzyme is in the cytosol and uses NADPH as a reductant for catalyzing a reversible reaction to trap ammonia during AMMONIA FIXATION
glutamate dehydrogenase
liberatiing glutamine from ammonia is done by blank
glutaminase
the only compound that can be completely oxidized by the krebs cycle
acetate via acetyl coA
except for amino acids which yield acetyl-CoA directly, all amino acids must be converted to blank prior to complete oxidation
pyruvate
most aa are ketogenic or glucogenic
glucogenic
aa whose carbon skeletons are converted to acetly coA may be used to form acetoacetate which is called blank
ketogenic
acetoacetate is a blank
ketone
ACETATE CANNOT GIVE RISE TO THE NET SYNTHESIS OF blank ALTHOUGH THE CARBONS FROM ACETATE CAN APPEAR IN blank
GLUCOSE
oxaloacetate is a blank in the krebs cycle
catalyst
net result of a turn of the TCA cycle
oxidation of acetate NOT oxaloacetate
urea formation occurs here
liver
this is located in the liver mitochondria and uses ammonia as the nitrogen donor in the urea cycle
carbamoyl phosphate synthetase I
this is present in the cytosol and is involved in pyrimidine synthesis
carbamoylphosphate synthetase II
this is in the urea cycle and catalyzes first step in arginine synthesis
ornithine transcarbamoylase
this is part of the urea cycle and catalyzes the reaction leading to the formation of argininosuccinate from citrulline and aspartate and requires atp
argininosuccinate synthetase
this cleaves arininosucccinate in the urea cycle to arginine and fumarate
argininosuccinase
part of the urea cycle where urea is made by the simple hydrolysis of arginine which is catalyzed by blank
arginase
this is a regenerating cycle much like oxaloacetic acid in the citric acid cycle
ornithine
lacking an enzyme of the urea cycle would lead to blank
ammonia toxicity
example of short term regulation of urea cycle by allosteric regulation of carbamoyl phosphate synthetase I by blank
nacetylglutamate
induction of the enzymes is an example of blank and an example is an increase in protein in the diet over several days
long term control
allosteric control of concentration of substrates in urea cycle is known as allosteric control and is blank
short term
arginine can be converted to citrulline and nitric oxide by blank
nitric oxide synthase
each enzyme subunit of nitric oxide synthase contains one blank and one blank and one blank and one blank
FMN, FAD, tetrahydrobiopterin, FE III heme
nitric oxide functions as a blank signal in regulation of vessel dilation and serves as a neurotransmitter
intracellular
ornithine can also be derived from blank and is used for synthesis of polyamines like putrescine
arginine
ornithine is coverted to putrescine by blank
ornithine decarboxylase
three aa that are used for synthesis of creatine
glycine, arginine, methionine
creatine and creatine phosphate can be converted back and forth to each other by blank
creatine kinase
first step of making creatine occurs is blank and blank and the methylation step occurs in the blank
kidney, pancreas, liver
excretion of creatinine in urine in a normal human is almost blank
constant
cancer chemotherapy is often directed at blank metabolism
FH4
blank is a one carbon carrier in one carbon metabolism
tetrahydrofolate
one carbon metabolism refers to sources of one carbon in more blank form than carbon dioxide
reduced
blank is a source of methyl groups in one carbon metabolism
s adenosylmethionine
the methylated derivative of FH4 is a blank because the reaction is irreversible
methyl trap
first step in synthesis of porphyrins
ALA synthase in mitochondria
porphobilinogen is synthesized by using this enzyme
ALA dehydrase
heme synthesis is accomplished via blank
porphyrins
