Biochem p. 104-108 Flashcards
AAs required during periods of
growth?
Arg and His “HAl is tall”
AAs that are in histones, which bind negatively charged DNA?
Arg and Lys
Excess —— is generated by urea cycle and
converted to urea and excreted by the kidneys.
nitrogen (NH3)
which enzyme is used to produce Carbamoyl
phosphate?
Carbamoyl phosphate synthetase I (mitochindria) CPs II (cytoplasm)
What is the required co-factor of Carbamoyl phosphate synthetase I?
N-acetylglutamate “NAG”
where does urea cycle occur?
mitochondria, cytoplasm
Using what enzyme and which substrate does carbamoyl phosphate become Citruline?
Ornithine transcarbamylase
Ornathine + Carbamoyl phosphate
which AAs is added into the Urea cycle?
Aspartate
Transport of ammonia by alanine and glutamate happens in which 2 cell types?
Muscle
Liver
Absence of N-acetylglutamate cause what path?
hyperammonemia.
Neonates that has poorly regulated respiration and body temperature, poor feeding, developmental delay and intellectual disability is seen in which 2 pathologies?
Carbamoyl phosphate synthetase I deficiency and N-acetylglutamate synth def both cause Hyperammonia.
T or F? The most common urea cycle disorder is a autosomal recessive disorder.
F! OTC is X-linked recessive
3 Finding in Ornithine transcarbamylase deficiency?
Orotic acid in blood and urine
decr BUN
symptoms of hyperammonemia
Excess of —– is converted to orotic acid which is part of the —– synthesis pathway.
carbamoyl phosphate, pyrimidine
Hypothyroid pts might be deficient in which AA?
Phenylalanine –> tyroxine
Pts having trouble with sleep might be deficient in what AA?
Tryptophan –> melatonin
Pts with porphyrias might have what AA def.?
Glycine –> Heme
G6PD dz might occur due to what AA def?
Glutamate –> Glutathion
Def of what AA can dec BUN and creatine?
Argenine
Male pt with angina and ED might have what AA deficiency?
Argenine… no NO production in the vessles
Pt suffering from albinism might be def in what AA?
Phenylalanine –> melanine
Pt with Parkinson disease might be def in which 2 AA?
Phenylalanine and Tyrosine –> dopamin
Which AA is constantly converted to its 2nd end product in Locus ceruleus in a pt with anxiety?
Phenylalanine–> NE–>EPi
In theory, if one is trying to increase his/her HDL levels, which AA and its cofactor are needed?
Tryptophan –> niacin using Vit B2 and vit B6
Severe vit B6 deficiency can theoretically worsen which 2 neurological disorders?
anxiety
Huntington disease
decr GABA
Which cofactors are needed to produce a neurotransmitter which is decr in anxiety and depression
Vit B6, BH4 used to make serotonin from tryptophan
AA used to produce neurotransmitter produced in Nucleus accumbens?
Glutamate makes GABA
Which AA is in excess and which is essential in PKU?
excess: phenylalanine
essential: tyrosine
Def of tetrahydrobiopterin cofactor is see in which path?
malignant PKU
Musty body odor is usually seen in
Disorder of aromatic amino acid metabolism
which artificial sweetener must PKU pts avoid?
aspartame, which contains phenylalanine.
(4) Finding is maternal PKU?
microcephaly
intellectual disability
growth retardation
congenital heart defects
Findings of dark connective tissue, brown pigmented sclerae, urine turns black on prolonged exposure to air are seen in a pathology that has an enzyme def in degradation which AA?
Tyrosine, in Alkaptonurea
Homogentisic acid is toxic to what type of collagen that causes debilitating arthralgias?
type ii for Cartilage
Enzyme def in Alkaptonurea?
Homogentisate oxidase
Enzyme deficiency in Maple Syrup dz (MSD)?
α-ketoacid dehydrogenase
Degradation of which branched amino
acids are blocked MSD? which one the most?
Isoleucine, Leucine, Valine— Leucine most
What should be supplemented in MSD?
thiamine supplementation (vit B1)
Which dz has this finding: intellectual disability, osteoporosis, marfanoid habitus,
kyphosis, lens subluxation, thrombosis, and atherosclerosis (stroke and MI).
Homocystinuria
What other dz do we find lens subluxation besides homocystinurea and how do we differentiate btw them?
Homocystinurea — downward and in
Marfan synd — upward and out
Name the 2 different enzyme deficiencies that can cause homocystinurea?
Homocysteine methyltransferase
Cystathionine synthase
What is another cause of homocystinurea?
decr affinity of cystathionine synthase for
pyridoxal phosphate/vit B6.
Tx: B6 and cysteine in diet
Which type of the homocystinureas can be treated with incr B12 and folate in diet?
the one with Cystathionine synthase defi
Cystinuria is a hereditary defect of renal — and intestinal
AA transporter that prevents reabsorption of:
PCT
Cysteine, Ornithine, Lysine, and Arginine (COLA).
How is Cystinuria diagnosed?
via Urinary cyanide-nitroprusside test
Tx of cystine stones?
urinary alkalinization (e.g., potassium citrate, acetazolamide) chelating agents (e.g., penicillamine)
Pt with intellectual disability, growth
retardation, seizures, fair skin, eczema, musty body odor is missing either an enzyme or a cofactor? what are thos?
phenylalanine hydroxylase
or
tetrahydrobiopterin cofactor
(7) findings in Homocystinurea:
intellectual disability osteoporosis kyphosis marfanoid habitus lens subluxation thrombosis atherosclerosis (stroke and MI).
Methionine synthase is seen in what dz? what another name for this enzyme?
Homocystinurea
homocysteine methyltransferase
How can strict vegans get an MI or stroke?
Vit B12 deficiency can cause Homocysteine to built up and cause atherosclerosis => MI or stroke.
Describe what Homocysteine converts into via which 2 enzymes:
Methionine Cystathionine –**–> Cysteine
- methionine synthase, vit B12
- cystathionine synthase, Vit 6, Serine
