Lecture 15 Flashcards
provides ~10% of our daily energy
amino acid catabolism
two places that deal with nitrogen metabolism
liver and kidney
the way we get rid of Nitrogen
urea!
glutamate funnel
all AA come into the liver and dump nitrogens onto α-KG and → Glutamate
this is Transamination
rxn catalyzed by Amino Transferase
amino transferase
enzyme that catalyses the transfer of amino groups to αKG
α KG
PLP
PLP
Pyridoxal phosphate
Role of PLP cofactor
allows transaminations by forming adducts to nitrogen and allowing the transfer with a keto acid
oxidative deamination
going from amino group to ammonia
deamination of glutamate to regenerate αKG and free nitrogens
glutamate dehydrogenase does
deaminates glutamate and regenerates αKG
glutamine
also carry nitrogen and can be deaminated
(delivered form muscles)
Alanine when deaminated..
generates pyruvate,
used to generate new glucose
role of pyruvate and alanine in movement of nitrogen between muscle and liver
the deaminated ala produces pyr ⇒ used for producing new glucose.
essentially: flow of lactate & ala out of muscle into liver when glucose is needed
key starting molecule in ornithine cycle
why?
urea!
becuase it is very stable, not very stable and have high pKA
very efficient in carrying nitrogen
function of urea cycle
safe way to get rid of NH3s
production of urine
where does urea cycle occur?
between the mitochondria and the cytosol
allosteric regulator of the rate limiting step in urea cycle
acetylglutamate synthase
rate limiting enzyme of urea cycle
Carbamoyl phosphate
essential amino acids are
amino acids that we cannot make and thus must consume:
One carbon metabolism cofactors: overview of function
Biotin: activates single carbon CO2 to add to things
Tetrahydrofolate: useful in dropping methy group on other AA
S-Adenosinylmethionine: methyl group donor
starting product for NADP
nicotinate (niacin)
PKU
phenylketourea: a deficiency in pathway of converting phenylalanine to tyrosine
PKU as prototype AA catabolic disease
deficiency in these enzymes leads to buildup of substance like phenylalanine. People can’t process things in diet
3H2 + N2 → 2NH3
Nitrogen fixation
nitrogenase funtion
(enzyme) fix nitrogen in the atmosphere
interplay between legumes and nitrogen fixing bacteria
legumes provide food for bacteria and bacteria fix nitrogen for the legume.
symbiotic relationship
Anammox bacteria
Anaerobic ammonium oxidizing bacteria
do nitrogen fixation without the prescence of O2
ammonia → nitrogen
with the help of hydrazine (fuel!)
hydrazine is
one of the best fuels, very reactive
organelle unique to annamox bacteria to contan hydrazine
Anammoxosome
coated by ladderane lipids (look like ladders) creating and intert chanber to hold hydrazine
Ladderane lipids
hydrocarbons that make up the hydrazine-proof chamber in annamox bacteria.
they are only seen in these bacteria
common route for nitrogen in mammals
N2→NH4+ →NO→ NH4+ in AA →(diet) conversion to needed compounds
collection of enzymatic activities
nitrogenase
nitrogenase at the heart of N2 fixation
very sensitive to O2, exergonic process.
Rhizobia
is a bacteria that does N2 fixation rxns by attaching to the roots of the legumes (organelle like) = simbiotic relationship between the plant and bacteria
Leghemoglobin
A legume-specific special version of hemoglobin, which binds to O2 and sucks it out of the solution to protect the Rhizobia
importance of glutamine in nitrogen anabolism
The synthesis of glutamine helps get NH4+ into metabolism
regulation of glutamine synthetase done by
Adenylation
2 layers of regulation: one from AMP addition which is regulated by UMP
covalent modification
2 layers of regulation of glutamine synthetase
uridylylation regulates adenylylation
amino acids are synthesized form ______ and _____
Krebs Clycle
and
Pentose phosphate patway
