Fate of Amino Acid: Carbon Skeleton Flashcards
____ of dietary proteins in the ____ and lumen of the ____ releases free amino acids into the bloodstream
Proteolysis of dietary proteins in the stomach and lumen of the small intestines releases free amino acids into the bloodstream
Protein digestion beings in the stomach by ____ and the enzyme ____
Protein digestion beings in the stomach by hydrochloric acid and the enzyme pepsin
What are three functions of hydrochloric acid in the stomach?
- Kill bacteria
- Denature Proteins
- Activate Pepsinogen
Gastric Phase of Protein Digestion
Pepsin in adult stomachs is secreded as ____. It is specific for peptide bonds formed by ____ (Phe, Tyr, Trp) or ____ amino acids (aspartic acid and glutamic acid)
Gastric Phase of Protein Digestion
Pepsin in adult stomachs is secreded as pepsinogen. It is specific for peptide bonds formed by aromatic (Phe, Tyr, Trp) or acidic amino acids (aspartic acid and glutamic acid)
The enzyme ____ digests milk protein (casein) in infants
The enzyme rennin digests milk protein (casein) in infants
Pancreatic Phase of Protein Digestion
Occurs in the ____ with enzymes secreted from the ____
____ activates ____ to become trypsin
Trypsin then activates ____ to ____ and ____ to ____
Pancreatic Phase of Protein Digestion
Occurs in the small intestine with enzymes secreted from the pancreas
Enteropeptidase activates trypsinogen to become trypsin
Trypsin then activates chymotrypsinogen to chymotrypsin and proelastase to elastase
Intestinal Phase of Protein Digestion
Intestinal enzymes are ____ and ____
The end product is ____, ____, and ____
Intestinal Phase of Protein Digestion
Intestinal enzymes are aminopeptidases and dipeptidases
The end product is free amino acids, dipeptides, and tripeptides
Ammino acids are actively transported across the intestinal mucosa (needs ____, ____ pump, ____ ions, and ____)
Ammino acids are actively transported across the intestinal mucosa (needs carrier, Na+ pump, Na+ ions, and ATP)
Neutral amino acid transport systems are notably important for the transport of ____ as a deficiency in this can lead to ____ disease
Neutral amino acid transport systems are notably important for the transport of Trp (tryptophan) as a deficiency in this can lead to Hartnup disease
Dibasic amino acid transport systems are notably immportant for the transport of ____ as deficiencies in this can lead to ____
Dibasic amino acid transport systems are notably immportant for the transport of cystine as deficiencies in this can lead to cystinuria
Hartnup’s Disease
Decreased levels of plasma ____
Urine excretion of ____
____ compounds increased
Decreased synthesis of ____ and ____ are responsible for neurological symptoms and pellegra like rash
Additonal symptoms include mental retardation and intermittent cerebellar ataxia
Hartnup’s Disease
Decreased levels of plasma tryptophan
Urine excretion of tryptophan
Indole compounds increased
Decreased synthesis of serotonin and pellegra are responsible for neurological symptoms and pellegra like rash
Additonal symptoms include mental retardation and intermittent cerebellar ataxia
Cystinuria is a disorder of the ________ reabsorption of filtered ____ and ____ amino acids (ornithine, arginine, lysine)
The inability to reabsorb ____ leads to accumulation and subsequent preciptation of stones of ____ in the urinary tract
Cystinuria is a disorder of the proximal tubule’s reabsorption of filtered cystine and dibasic amino acids (ornithine, arginine, lysine)
The inability to reabsorb cystine leads to accumulation and subsequent preciptation of stones of cystine in the urinary tract
Note: Cystinuria is distinct from cystinosis, a rare defect in the transport of cystine out of lysosomes that results in the foramtion of cystine crystals within the lysosome and tissue damage
Amino acids can be broken down into:
- ____ which can:
- Be used for biosynthesis of AAs, nucleotides, and amines
- Be converted to ____ and enter the urea cycle to be converted to ____ to be exreted
- Carbon skeletons which can be converted to ____ and enter the ____ cycle
Amino acids can be broken down into:
-
Ammonia which can:
- Be used for biosynthesis of AAs, nucleotides, and amines
- Be converted to carbamyl phosphate and enter the urea cycle to be converted to urea to be exreted
- Carbon skeletons which can be converted to a-keto acids and enter the citric acid cycle
____ amino acids give rise to pyruvate or C4 or C5 TCA cycle intermediates. All such compounds can contribute to ____
____ amino acids give rise to acetyl-CoA and excess acetyl-CoA may be converted to ________
Glucogenic amino acids give rise to pyruvate or C4 or C5 TCA cycle intermediates. All such compounds can contribute to gluconeogenesis
Ketogenic amino acids give rise to acetyl-CoA and excess acetyl-CoA may be converted to ketone bodies
Amino acids ____ and ____ can be converted to fumarate
Amino acids ____, ____, and ____ can be converted to propionyl-CoA which can be converted to succinyl-CoA
Amino acids phenylalanine and Tyrosine can be converted to fumarate
Amino acids isoleucine, Valine, and methionine can be converted to propionyl-CoA which can be converted to succinyl-CoA
Amino acids can be dervied from ____, ________ cycle, and the ________ pathway
Amino acids can be dervied from glycolysis, citric acid cycle, and the pentose phosphate pathway
How can alanine participate in the TCA cycle?
Alanine can be converted to pyruvate via ALT
How can asparagine enter the urea cycle?
Asparagine can be converted to aspartate via AST
Phenylalanine and Trysosine can ultimately be converted into ____ which participates in the TCA cycle
Phenylalanine and Trysosine can ultimately be converted into fumarate which participates in the TCA cycle
Isoleucine, Valine, methionine, and threonine can be converted to ____ which is converted to ____, which is converted to ____ to participate in the TCA cycle
Isoleucine, Valine, methionine, and threonine can be converted to propionyl-CoA which is converted to methylmalonyl-CoA, which is converted to Succinyl-CoA to participate in the TCA cycle
What can glutamate be converted into to participate in the TCA cycle?
Glutamate can be converted to a-ketoglutarate to participate in the TCA cycle
The first step in amino acid degredation is the removal of ____
This occurs via an aminotransferase which requires ____ as coenzyme
The first step in amino acid degredation is the removal of nitrogen
This occurs via an aminotransferase which requires PLP (Vitamin B6) as a coenzyme
Note: All transamination reactions require PLP
ALT transfers an a-amino group from ____ to ____ to form ____ and ____
(____ can be oxidatively deaminated to yield an ____ ion)
ALT transfers an a-amino group from alanine to a-ketoglutarate to form pyruvate and glutamate
(glutamate can be oxidatively deaminated to yield an ammonium ion)
AST converts ____ and ____ to ____ and ____
AST converts aspartate and a-ketoglutarate to oxaloacetate and glutamate
Homocytinuria can be cause by (4 examples):
Homocytinuria can be cause by (4 examples):
- Cystathionine B-synthase defect/deficiency
- Methionine synthase defect/deficiency
- Vitamin B6 deficiency
- Vitamin B12 deficiency
- Folate deficiency
What is methyl-malonic acidemia caused by?
Levels of what increase in the blood?
This results in (2 examples):
Methyl-malonic acidemia is caused by:
Methylmalonyl-CoA mutase defect/deficiency
Levels of what increase in the blood?
Methylmalonic acid (methylmalonate)
This results in (2 examples):
Metabolic acidosis and developmental problems
Oxidation of Odd Chained Fatty Acids
Propionic acidemia is caused by a ________ deficiency (an autosomal recessive metabolic disorder)
This condition is very serious and requies a strict dietary regime and ____ supplementation
Monitored by measuring ________ in the blood
Presents in the early neonatal period with (4 examples):
Oxidation of Odd Chained Fatty Acids
Propionic acidemia is caused by a proprionyl-CoA carboxylase deficiency (an autosomal recessive metabolic disorder)
This condition is very serious and requies a strict dietary regime and biotin supplementation
Monitored by measuring propionic acid in the blood
Presents in the early neonatal period with:
- Progressive encaphalopathy
- Heart/liver damage
- Seizures
- Delays in normal development
Oxidation of Odd Chained Fatty Acids
Methylmalonic aciduria can occur because of defects in ________ or in defects in ____ metabolism
Increased methlmalonic acid levels are a sensitive indicator of mild ____ deficiency
Treatment involves ____ restriction using formula deficient in valine, isoleucine, methionine, and threonine
Infants are well at birth but become ill on protein feeding and develop lethargy, failure to thrive, muscular hypotonia, respiratory distress, and recurrent vomiting and dehydration
Oxidation of Odd Chained Fatty Acids
Methylmalonic aciduria can occur because of defects in methylmalonyl CoA mutase or in defects in vitamin B12 metabolism
Increased methlmalonic acid levels are a sensitive indicator of mild vitamin B12 deficiency
Treatment involves protein restriction using formula deficient in valine, isoleucine, methionine, and threonine
Infants are well at birth but become ill on protein feeding and develop lethargy, failure to thrive, muscular hypotonia, respiratory distress, and recurrent vomiting and dehydration
Maple Syrup Disease
Defective ________
Urine has odor of ________
Mental and physical retardation unless patients are placed on a diet low in ____, ____, and ____ early in life
BCAAs play a key role in maintaining the supply of the neurotransmitter ____
Maple Syrup Disease
Defective branched-chain a-keto acid dehydrogenase complex
Urine has odor of maple syrup
Mental and physical retardation unless patients are placed on a diet low in valine, isoleucine, and leucine early in life
BCAAs play a key role in maintaining the supply of the neurotransmitter glutamate
Maple Syrup Disease
Defective ________, this enzyme also requires (5 examples):
Maple Syrup Disease
Defective branched-chain a-keto acid dehydrogenase complex, this enzyme also requires:
- Thiamine pyrophosphate (TPP) from thiamine (vitamin B1)
- Lipoic acid
- CoA from vitamin B5
- FAD from riboflavin (vitamin B2)
- NAD (vitamin B3)
Phenylketonuria
Caused by mutations in the gene encoding ________
Results in a build up of ____ which gets converted to ____ and ____
Phenylketonuria
Caused by mutations in the gene encoding ________
Results in a build up of ____ which gets converted to ____ and ____
Phenylketonuria
Mutation in ________ causes ____ to accumulate in body fluids and ____ derivatives to not be made
________ odor in urine and sweat
Treatment with ____ diet. If untreated, drastic IQ reduction
Phenylketonuria
Mutation in phenylalanine hydroxylase causes phenylalanine to accumulate in body fluids and tyrosine derivatives to not be made
Mouse-like odor in urine and sweat
Treatment with low phenylalanine diet. If untreated, drastic IQ reduction
Deficiency in ____ also causes phenylketonuria
Deficiency in tetrahydrobiopterin (aka (BH4/THB) also causes phenylketonuria
A deficiency in ________ or any of the enzymes of ____ synthesis leads to hyperphenylalaninemia and decreased synthesis of ____ and ____
A deficiency in dihydropteridine reducase or any of the enzymes of BH4 synthesis leads to hyperphenylalaninemia and decreased synthesis of catecholamines and serotonin
Type II tyrosinemia is an inborn error of tyrosine metabolism caused by a deficient ________ enzyme. Results in ____ accumulation in plasma, urine, and tissue, causing ________ and ________
Of note this enzyme also requires PLP (vitamin B6)
Type II tyrosinemia is an inborn error of tyrosine metabolism caused by a deficient Tyrosine Aminotransferase (TAT) enzyme. Results in tyrosine accumulation in plasma, urine, and tissue, causing corneal ulcers and palmoplantar hyperkeratosis
Of note this enzyme also requires PLP (vitamin B6)
Alkaptonuria (Black Urine Disease)
____ accumulates in urine (turns urine dark when left standing)
Often benign but sclera of the eyes and ear wax may be pigmented.
Alkaptonuria (Black Urine Disease)
Homogentisate accumulates in urine (turns urine dark when left standing)
Often benign but sclera of the eyes and ear wax may be pigmented.
