10/12 Energy from Proteins Flashcards
what can all 20 AAs be broken down into
pyruvate
acetyl-CoA
TCA intermediate
what molecules picks up the amine group in transamination rxns
a-ketoglutarate —> glutamate
product of transamination rxn
a-keto acid
hormones of fasted state and effects
when blood glucose and insulin are low, counter regulatory hormones are released (glucagon, cortisol, (nor)epinepherine
mm do not have glucagon receptors
where do breakdown products go after leaving mm/peripheral tissues
alanine/glutamine –> liver
BCAAs and glutamine –> small intestines and kidneys
which AAs are major blood nitrogen carriers
alanine and glutamine
what product of AA metabolism is toxic
ammonia (from glutamate)
eliminated through urea cycle
can cross blood-brain barrier, interferes with neurotransmitters
which AA are exclusively ketogenic
leucine and lysine
what happens to ketogenic AAs
come to liver, converted into Acetyl-CoA (or acetylacyl-CoA), can then become a fatty acid (TAGs)
what happens to glutogenic AAS
come to liver, converted to pyruvate or oxaloacetate (or other TCA intermediates), can then become glucose (glycogen)
two enzymes for transamination
transaminase
aminotransferase
which aminotransferase enzymes are on a standard serum panel to check for liver damage
ALT (alanine aminotransferase) (liver prob)
AST (aspartate aminotransferase) (liver or muscle prob)
prefered E sources in fed state
glucose and FAs
AAs are used for synthetic processes
what are the BCAAs
leucine, isoleucine, valine
cofactor for BCAA transamination
B6
cofactor for further breakdown of BCAAs
B1 (thiamine)
products of further breakdown of BCAAs
NADH, FADH2, acetyl-CoA, succinyl-CoA
cofacts req for biosynthesis of succinyl-CoA
(B1/thiamine)
B7 biotin
B12 cobalamin
what enzyme is deficient in maple syrup urine disease
AR loss of branched-chain keto acid dehydrogenase
maple syrup urine disease, symptoms/Tx
by day 4-7 of life, accumulation of BCAAs causing sweet-smelling urine, progressive neuro damage, seizures, spastic quadriparesis
Tx: dietary restrictions of BCAAs
role of blood alanine
to liver, converted to pyruvate for gluconeogenesis
enzyme: ALT
role of blood glutamine
to liver: urea cycle (most nitrogen disposal)
to kidneys: to be eliminated as ammonium (maintains urine and blood pH)
location of urea cycle
liver, mitochondria then cytoplasm
accumulation of first nitrogen in urea cycle
enzyme: carbamoyl phosphate synthatase I, reqs E, in mitochondria
product: carbamoyl phosphate
accumulation of second nitrigen in urea cycle
enzyme: ornithine transcarbamoylase, reqs E, sends prod to cytoplams
product: citrulline
final product of urea cycle
urea (two N)
from arginine
lab value for renal failure
high BUN (blood urea nitrogen)
lab value for liver problems
high ammonia
ornithine transcarbamoylase deficiency
x-linked
chronically elevated blood ammonia results in neuronal damage and mental retardation
Tx: low protein diet, dialysis
Labs: high ammonia, low BUN, respiratory alkalosis, low citrulline
