Metabolism III Flashcards
hyperammonemia
excess NH4+ - deplete a-KG
-inhibition of TCA cycle
tx - limit protein in diet
lactulose - acidify GI tract
rifamaxin - decreased colonic ammoniagenic bacteria
benzoate - bind AAs
N-acetylglutamate
cofactor for CPS-1
-deficient - same as CPS-1 deficiency
get hyperammonemia
CPS-1 deficiency
hyperammonemia neonate poorly regulate temp/respiration poor feeding developmental delay intellect disability
MC urea cycle disorder
OTC deficiency
-X-linked recessive
OTC deficiency
ornithine transcarbamylase
excess carbamoyl phosphate > orotic acid
see orotic aciduria, decreased BUN, hyperammonemia
orotic aciduria
megaloblastic anemia
AA for dopamine, NE, E
phenylalanine
converted to tyrosine > dopa
melatonin AA source
tryptophan
require BH4 and B6
AA source of NAD+
tryptophan
require B6
AA source heme
glycine
require B6
AA source GABA
glutamate
require B6
AA source nitric oxide
arginine
AA source creatinine
arginine
AA source urea
arginine
tyrosinase deficient
albinism
converts DOPA > melanin
deficient phenylalanine hydroxylase
PKU
converts phenylalanine > tyrosine
deficient tetrahydrobiopterin
BH4
PKU - cofactor for phenylalanine hydroxylase
deficient homogentisate oxidase
alkaptonuria
black pigment
converts homogentisic acid > maleyacetoacetic acid
carbidopa
inhibit DOPA decarboxylase
cortisol
stimulate phenelethanolamine-N-methyltransferase
convert NE > E
phenylketonuria
PKU
deficient phenylalanine hydroxylase
or deficient tetrahydrobiopterin (BH4) - cofactor
auto recessive
musty body odor
excess phenylketones in urine
phenylketones
phenylacetate, phenyllactate, phenylpyruvate
-in urine of pt with PKU
aspartame
artificial sweetener
contains phenylalanine
should be avoided PKU
tx PKU
restrict phenylalanine in diet
also - supplement tyrosine (bypass enzyme deficiency)
maple syrup urine disease
deficient a-ketoacid DH
cannot break down branched chain AAs
-leucine, isoleucine, valine
urine smells of burnt sugar
auto recessive
restricted AAs in maple syrup urine disease
no branched chain AAs
-leucine, isoleucine, valine
also - thiamine supplementation
alkaptonuria
deficiency homogentisate oxidase
-pigment forming homogentisic acid accumulate
auto recessive
dark CT, brown sclera, urine black after exposure to air
homocystinuria
auto recessive
3 types:
1 -cystathione synthase deficiency
-tx decreased methionine, increased cysteine, B12, folate
2 -decreased affinity cystathione synthase for pyridoxal P
-tx vit B6 and cysteine
3 -homocysteine methyltransferase deficiency
-tx methionine in diet
clinical homocystinuria
elevated homocysteine in urine intellect disability osteoporosis marfanoid habitus kyphosis lens subluxation thrombosis atherosclerosis
cystinuria
auto rec
defect renal PCT
-and intestinal AA transporter
of cysteine, ornithine, lysine, arginine (COLA)
COLA
defective transport in cystinuria
cysteine
ornithine
lysine
arginine
hexagonal kidney stones
cystinuria
tx cystinuria
urine alkalinization - potassium citrate, acetazolamide
chelating agent - penicillamine
diagnosis of cystinuria
urinary cyanide-nitroprusside test
cystine
2 cysteine - connected by disulfide bond
glucagon regulation of glycogen
activate adenylate cyclase
> increased cAMP
> increased protein kinase A
> activation glycogen phosphorylase kinase
> increased activity glycogen phosphorylase
> breakdown glycogen to glucose
epinephrine regulation of glycogen - beta receptors
activate adenylate cyclase
> increased cAMP
> increased protein kinase A
> activation glycogen phosphorylase kinase
> increased activity glycogen phosphorylase
> breakdown glycogen to glucose
epinephrine regulation of glycogen - alpha receptors
release of Ca from endoplasmic reticulum
> activation glycogen phosphorylase kinase
> increased activity glycogen phosphorylase
> breakdown glycogen to glucose
insulin regulation of glycogen
tyrosine kinase receptor dimerize
> active protein phosphatase
> activate glycogen synthase
> more glucose to glycogen
glycogen branches
a-1,6
glycogen linkages
1-1,4
glycogenolysis
glycogen > glucose 1-P > glucose 6-P > ATP
glycogen phosphorylase
liberates glucose 1-P from glycogen
debranching enzyme
4-a-D glucanotransferase - when 4 glucose on branch - transfer 3 to the long chain
a-1,6 glucosidase - when 1 glucose on branch (after 4-a-D) - breaks it off to release glucose 1-P
