Test 2: Protein Metabolism Flashcards
How many AA are needed for gluconeogenesis?
18
What two proteins cannot be used for gluconeogenesis?
leucine and lysine***
If the liver is not functioning properly, ammonia will _______ and urea will _______.
increase, decrease
What is the rate limiting enzyme of the urea cycle?
carbamoyl phosphate synthetase 1 (EC 6, 3, 4, 16)***
About ____% of urea is filtered and the rest is reabsorbed at the distal tubule.
40-50
What is the principle of the biuret test?
copper binds to peptide bond to measure AA
What is the alpha carbon?
the carbon connected to the functional group
a protein is an amino acid chain that consists of more than ____ peptides.
100
What makes a peptide bond?
NH2 group linking the w/
COOH group of another,
forming a peptide bond.
What are the essential AA?
: Histidine (His), Isoleucine (Ile), Leucine (Leu), Lysine (Lys), Methionine (Met),
Phenylalanine (Phe), Threonine (Thr), Tryptophan (Trp), Valine (Val)
9 in total
pH at which overall net charge is neutral and the proteins stops moving
Isoelectric point (pI)
AA: equal # of opposing charge
Ionizable group at physiological pH of ____
7.4
Protein synthesis is used to make what types of proteins?
- plasma proteins
- Intracellular proteins
- Structural proteins
Non Protein Nitrogen compound synthesis includes…
Purine, Pyrimidine, porphyrins, Creatine, Urea, Histidine, Thyroxine, Epi, Coenzyme NAD+
Amino acids are used for ____% of the total energy supply.
12-20
this energy substrate is not as good as fat or glucose
Pyruvate is an intermediate in the conversion of what amino acids to acetyl-CoA?
threonine, glycine, Serine, Cysteine, and Alanine (catabolic pathway)
The catabolic pathways of what amino acids are long and complex?
lysine, tryptophan, phenylalanine, tyrosine, and leucine
The catabolic pathways of what amino acids eventually get converted to alpha-ketoglutarate?
Arginine, proline, Histidine, Glutamine, and Glutamate
-Propionyl-CoA and L-methylmalonyl-CoA are intermediates in conversion of these amino acids to succinyl-CoA
-Methylmalonyl-CoA mutase is a vitamin B12 requiring enzyme
catabolic pathways of Methionine, Isoleucine, and valine
What are the metabolic disorders of amino acid metabolism? (most are genetic)
-Phenylketonuria
-Tyrosinemia
-Alkaptonuria
-Maple syrup urine disease (MSUD)
-Isovaleric acidemia
-Homocystinuria
-Cystinuria
Inborn error of “PHENYLALANINE” METABOLISM
Phenylketonuria (PKU)
what prevents the conversion to tyrosine with PKU?
Defective phenylalanine hydroxylase*
PKU causes the accumulation of…
phenylalanine/phenylpyruvic acid (phenylketone)
Can lead to severe metabolic acidosis & neurological problems (effects dopamine)
■ Can be controlled by monitoring diet
How is anion gap calculated?
sodium - (chloride + bicarbonate)
Inherited disorder that leads to tyrosine accumulation.
Tyrosinemia
what causes Tyrosinemia?
Loss/defect in enzyme that catabolizes tyrosine in liver —> build up of tyrosine
Which Tyrosinemia is the most severe?
What causes it?
Type 1
decreased levels of fumarylacetoacetate hydrolase
What are the symptoms of type 1 Tyrosinemia?
failure to thrive, jaundice, cabbage-like odor, nose bleeds (weak capillaries)*
liver & kidney failure, neuropathy & hepatic tumors
(rare) deficiency of tyrosine aminotransferase.
Type 2 Tyrosinemia
What are the symptoms of type 2 Tyrosinemia?
Excessive tearing, photophobia, eye pain, lesions and mental retardation
(very rare) Deficiency of 4-hydroxyphenylpyruvate dioxygenase
Type 3 Tyrosinemia
What are the symptoms of type 3 Tyrosinemia?
mild retardation, seizures and intermittent ataxia
What is known as “Black urine” or “black bone” disease?
Alkaptonuria
What causes Alkaptonuria?
Defect in homogentisate oxidase
What happens physiologically with Alkaptonuria?
-Increased homogentisic acid (HGA) - intermediate breakdown product
-HGA deposits in connective tissue, cartilage, & skin and heart - darkening of skin, urine and arthritis
Rare genetic condition that causes urine to turn black when exposed to air,
kidney and prostate calculi, and heart problems
Alkaptonuria
What causes dopamine to be effected with PKU?
Phenylalanine cannot be converted tyrosine to make L-DOPA —> dopamine
What are the three branched chain amino acids (BCAAs)?***
valine
isoleucine
leucine
Disorder that involves a defect in α-ketoacid dehydrogenase.
Maple syrup urine disease
Maple syrup urine disease:
individual cannot properly break down …
the BCAAs (Val, Ile, Leu)
-Leads to an accumulation of the BCAAs & their respective keto-acids
What are the symptoms of Maple syrup urine disease?
-Poor feeding, vomiting, lethargy, seizures, and developmental delays.
-Urine has a characteristic “maple syrup” odor to it.
Rare disorder involved in the proper catabolism of leucine
Isovaleric acidemia
Isovaleric acidemia leads to increased _____________.
isovaleric acid
Isovaleric acidemia:
Defect in what enzyme?
isovaleryl-CoA dehydrogenase (IVD) enzyme
What are the symptoms of Isovaleric acidemia?
Poor feeding, sweaty feet, vomiting, lethargy, and progress to coma
What causes the distinctive odor of sweaty feet in Isovaleric acidemia?
Increase in isovaleric acid
Inherited disorder involving cystathionine β-synthase (CBS) **accumulation of homocysteine & methionine
Homocystinuria
What are the two cysteine disorders?
-Homocystinuria
-Cystinuria
Individual cannot properly metabolize methionine/homocysteine
Homocystinuria
What are the symptoms of Homocystinuria?
lens dislocation in eye, increase in blood clots, skeletal abnormalities, &
learning problems.
Condition characterized by build up of cysteine caculi in kidney & bladder
■ as a result of inability to reabsorb cysteine
Cystinuria
Is Cystinuria caused by a defective metabolic pathway?
NO
Cystinuria:
Inherited disorder of cysteine transport ___________ (SLC3A1 or SLC7A9)
■ Defect in the transport of cysteine back in to the body
proteins (not enzymes)
What is an enzyme that does the same action as Methionine synthase?
Homocysteine
Methyl transferase
(Homocysteine —-> Methionine)
Conversion of homocysteine to cystathionine is done by….
Cystathionine
Β-synthase (TRANSSULFULATION)
-Glutathione mobility to cells to replenish glutathione
-important enzyme of the liver
Gamma glutamyl transferase (GGT)
What can an increased GGT level signify?
alcohol toxicity
