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What does it mean to be Ammonotelic?
Example?
- Excrete ammonia (which would poison us if floating around in our bodies)
- Fish
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What does it mean to be Uricotelic?
Example?
- Excrete uric acid (guano)
- Birds
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What does it mena to be Ureotelic?
Example?
- Excrete non-toxic, water-soluble urea
- Land animals, US!
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Nitrogen Balance
Nitrogen intake matches nitrogen excreted
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Positive Nitrogen Balance
- Excess Nitrogen ingested over excreted
- eg. Pregnancy and Growth
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Negative Nitrogen Balance
- Nitrogen output exceeds intake
- eg. Surgery, cancer, Kwashiorkor, Marasmus
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How much total protein is turned over daily?
- 1-2% of total body protein/day turnover
- -2 other fun facts
- 75% of the liberated amino acids are reutilized
- 25% nitrogen converted to urea and carbon skeleton converted to metabolic intermediates
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What can produce urea?
Liver
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Glucose-Alanine Cycle
Glucose converted to Alanine to enter blood stream and then liver, Alanine convereted to glutamate, NH4+, and urea or Glucose to then be excreted into the blood stream.
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What are the steps involved in Nitrogen catabolism?
- 1. Transamination (remove amino group)
- 2. Oxidatibe deamination of glutamate
- 3. Ammonia transport (to liver)
- 4. Reactions to the urea cycle (5 enzymes involved)
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Aminotransferases catalyze transamination
amino acid + keto acid <--(aminotransferase)--> keto acid + amino acid
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Alanine come from...?
Serine comes from...?
What organ are they going to and what is excreted?
- Alanine- Muscle, gut, kidney
- Serine- kidney
- Liver --->Urea, glucose
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Aspartate + alpha-ketoglutarate (amino group) <---->Oxaloacetate + glutamate converted by what enzyme?
- Aspartate Aminotransferase (AST)
- SGOT
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Alanine + alpha-ketoglutartate <---> pyruvate + glutamate converted by which enzymes?
- Alanine Aminotransferase (ALT) --->
- (SGPT) <--
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Glutamate Dehydrogenase, a rate limiting enzyme in amino acid catbalism is inhibited by what?
- GTP, ATP, NADH, NADPH
- High energy
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Glutamate Dehydrogenase, a rate limiting enzyme in amino acid catabolism is stimulated by what?
ADP, GDP
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Serine--Serine Dehyratase--> Leads to?
Pyruvate and NH4+
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Threonine --Threonine Dehyratase--> Leads to?
alpha-ketobutyrate and NH4+
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Ammonia is converted to?
Where are the carbons and nitrogens from?
- Urea
- Carbon from CO2
- 1 Nitrogen from Aspartate
- 1 Nitrogen from Ammonia
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Where does urea cycle occur?
Parts in mitochondria and parts in cytoplasm of Liver cells
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What are the amino acids is the urea cycle?
- Ornithine
- Citrulline
- Arginine
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What does Aspartate become in urea cycle?
Fumarate
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What is fumarate converted to?
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Hyperammonenemia Type I
- CPSynthetase I deficiency
- 1st emzyme toxic, serious condition
-
Hyperornithinemia, hyperammonemia, and homocitrullinuria syndrome (HHH Syndrome)
Ornithine transporter defect
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Hyperammonemia Type II
- Ornithine Transcarbamoylase deficiency
- X-linked disease
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Citrullinemia
Argininosucinate synthetase deficiency
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Argininosuccinicaciduria
Argininosuccinase or argininosuccinate lyase deficiency
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Hyperargininemia
Arginase deficiency
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What amino acids are purely ketogenic?
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What amino acids are ketogenic and glucogenic?
- Phenylalanine
- Tryptophan
- Tyrosine
- Isoleucine
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What enzymes are purely glucogenic?
- Alanine
- Cysteine
- Glycine
- Serine
- Asparagine
- Aspartate
- Methionine
- Threonine
- Valine
- Arginine
- Glutamate
- Glutamine
- Histidine
- Proline
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Phenylalanine + O2 + tetrahydrobiopropterin (cofactor) oxidized by what? To What?
--Phenylalanine hydroxylase--> Tyrosine + H2O + quinonoid dihydrobiopterin
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Methionine is degraded into what?
Succinyl CoA
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Citrullinema
- Argininosuccinase deficiency
- Lethargy, seizures, reduced muscle tension
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Tyrosinemia
- Various enzymes of tyrosine degradation deficiency
- Weakness, self-mutilation. liver damage, mental retardation
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Albinism
- Tyrosinase deficiency
- Absence of pigmentation
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Homocystinuria
- Cystathionine Beta-synthase deficiency
- Scoliosis, muscle weakness, mental retardation, thin blonde hair
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Hyperlysinemia
- alpha-Aminoadipic semialdehyde dehydrogenase deficiency
- Seizures, mental retardation, lack of muscle tone, ataxia
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Histidinemia
Histidase deficiency
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Glycinuria
Defect in reanl tubular reabsorption
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Cystine-lysinuria
Defect in renal tubular reabsorption
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Cystinosis
Cystine storage disease
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Alkaptonuria
hoomogentisate oxidase deficiency
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Maple syrup urine disease (branched-chain ketonuria)
alpha-ketoacid decarboxylase complex defect
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Phenylketonuria
Classic PKU or Type 1
Types II and III
Types IV and V
- Classic PKU or Type 1- Phenylalanine hydroxylase deficiency
- Types II and III- dihydrobiopterin reductase deficiency
- Types IV and V- dihydrobiopterin biosynthesis defect cofactor not avaliable
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Essential amino acids
must be obtained from diet
-
Nonessential amino acids
can be synthesized
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What is the entry point for ammonia?
Glutamate
-
Glutamate dehydrogenase
- Mitochondrial enzyme present in mammals mainly used for catabolism
- NH4+ + alpha-ketoglutarate + NAD(P)H + H+ --Glutamate dehydrogenase--> Glutamate + NAD(P)+ + H2O
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Glutamine Synthetase
Adds NH4+ to Glutamate to convert it to Clutamine
-
Glutamate Synthase
- No present in animals predominantly in plants
- 2 Glutamate generated from alpha-ketoglutarate and gluamine with the addition of NADPH
-
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Glutamate (AA) + Pyruvate (alpha-keto acid) <----> Alpha-ketoglutarate (alpha-keto acid) + Alanine (Amino acid)
What enzyme?
ALT a transaminase
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Glutamate (AA) + Oxaloacetate (alpha-keto acid) <----> Alpha-ketoglutarate (alpha-keto acid) + Aspartate (Amino acid)
What enzyme?
AST a transaminase
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What does Transamination require?
Vitamin B6
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Histidine comes from?
- Ribose 5-Phosphate
- Purely from PPP
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Serine comes from?
And leads to?
- 3-Phosphoglycerate
- Leads to Cysteine and Glycine
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Cysteine and Glycine come from?
Serine which comes from 3-Phosphoglycerate
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Phenylalanine and Tryptophan come from?
What do they lead to?
- Phosphoenolpyruvate and Erthrose 4-phosphate
- Tyrosine
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Aspartate comes from?
And leads to?
- Oxaloacetate
- Asparagine, Methionine, Threonine. Lysine
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Alainine, Valine, and Leucine come from?
Pyruvate
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Glutamate comes from?
Leads to?
- alpha-ketoglurarate
- Glutamine, Proline, Arginine
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Glutamine, proline, arginine come from?
Glutamate
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Vitamin B9 is required for?
Tetrahydrogolate formation which is needed during amino acid synthesis
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One carbon groups carried by tetrahydrofolate?
- -CH3 Methyl
- -CH2- Methylene
- -CHO Formyl
- -CHNH Formimino
- -CH-- Methenyl
-
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Formaldehyde
Intermediate oxidation state
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Formic acid
Most oxidized
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Cysteine can be synthesized from?
- Methionine
- Requires SAM (ethyl donor group)
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Feed back inhibition can be?
Linear and branched
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Isoleucine _______ Threonine deaminase and Valine ______ it
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Aspartokinase can be inhibited by what?
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