Protein Metabolism Flashcards
Removal of the a-amino group is a process called _________?
Deamination
What are the sources of the nitrogen that appears in urea?
NH3, Primarily from acid catabolism,
provides one N urea and Asp provides the other.
Asparginase is used to treatchildhood acute lymphoblastic leukemia.
What is the biochemical basis of this treatment?
Asparginase is a treatment for ALL because it deamidates circulating Asn to Asp.
Rapidly dividing leukemia cells require Asn for growth and have limited capacity to synthesize it.
What coenzymes are required by BCKD, the enzyme that oxidatively decarboxylates the alpha-keto acid derivatives of the BCAA’s?
BCKD ,a mitochondrial enzyme, requires:
Co-substrate:
1. NAD
2. CoA
Prosthetic groups:
1. TTP
2. Lipoic acid
3. FAD
BC ka Dae?
(Na Co, True Love FADe)
This is the phase where carbon skeletons of a-keto acids are converted to common intermediates of energy producing metabolic pathways.
Second Phase of AA Catabolism
Identify the enzyme used in oxidative deamination.
Glutamate dehydrogenase
Identify the AA which do not undergo transamination?
- Lysine
- Threonine
- Proline
- Hydroxyproline
(HTLP)
Urea cycle happens in which organ of the body?
Liver only
Urea cycle happens in which part/s of the cell?
It occurs in both mitochondria and cytosol
Identify the substrates used in urea cycle.
- NH3
- Aspartate
- CO2
This is the allosteric activator for the rate limiting step in urea cycle.
N-acetylglutamate
What is the most common hereditary hyperammonemia?
Ornithine transcarbomylase deficiency
What are the 2 purely ketogenic AAs?
- Lysine
- Leucine
( II ketogenic)
Ketoacid of pyruvate
Alanine
Ketoacid of oxaloacetate
Aspartate
Ketoacid of a-ketoglutarate
Glutamate
Carnitine comes from which amino acid?
Lysine
Identify the derivatives of Methionine.
- S-adenosylmethionine
- Creatine
- Polyamines
Identify the derivatives of Tryptophan.
- Serotonin
- Niacin
- Melatonin
( Tryp Mo Sya No? )
Alkaptonuria is a congenital deficiency of __________ in the degradative pathway of tyrosine, leading to build up of homogentisic acid.
Homogentisate oxidase
Identify the disease associated with defect in fumarylacetoacetate hydrolase?
Tyrosinemia Type I
Cystinuria is an inherited defect of renal tubular amino acid transporter for ________,__________,___________ and __________ in the PCT of the kidneys.
- Cysteine
- Ornithine
- Lysine
- Arginine
( COLA)
Identify the co-factor of ALA Synthase.
Vitamin B6 / Pyridoxine / Pyridoxal-5-Phosphate
Lead inactivates which two enzymes in the heme synthesis pathway?
- ALA Dehydratase
- Ferrochelatase
Porphyria cutanea tarda is the deficiency of which enzyme?
Uroporphyrinogen Decarboxylase
Acute intermittent porphyria is the deficiency of which enzyme?
Hydroxymethylbilane decarboxylase/
Uroporphyrinogen I synthase
What is the basis of ethanol- related hypoglycemia?
The rise in NADH/ NAD+ ratio as a result of ethanol metabolism by ADH and ALDH, enzymes that oxidize ethanol and acetaldehyde, respectively, as their coenzyme NAD+ is reduced.
What group of amino acid is metabolized primarily by muscle rather than by liver?
Branched Chain Amino Acids are catabolized primarily by muscles, the primary location of BCAA transaminase that initiates their degradation.
BCAAs: Leucine, Isoleucine, Valine
True or False. Peptide transport protein allows uptake of dipeptide and tripeptides.
True. Peptides are largely digested in the cytosol. Constituent AAs for export to the body.
Amino acid that is likely elevated in a child with relatives having darkening of the urine when left standing?
Homogentisate
Alkaptonuria: is caused by a defective homogentisic acid oxidase.
Amino acid that is likely increased in the urine in a child with mental retardation, difficulty with vision, fair complexion, malar erythema, bilateral dislocated lenses, long slender hands with blood test cystathione concentration below normal.
Ans. Methionine
Homocystinuria: homocysteine is a metabolite of methionine
Mechanism on how lactulose acts to treat hyperammonemia.
Fermentation of lactulose results in acidification of gut contents so that ammonia produced by intestinal bacteria is trapped as ammonium that cannot be diffused into the blood stream.
Enzyme that is defective in an infant experiencing feeding difficulty, generalized hypotonia of the limbs , strange eye movements causing eyeballs to rotate up several times a day with significant aminoaciduria and aminoacidemia.
L- amino acid oxidase in Oculogyric Crisis
The fatty liver in children with kwashiorkor is the result of this abnormality
Lack of substrates for protein synthesis in the liver.
