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Metabolism of amino acids - exercise -. Vladimíra Kvasnicová. Choose essential amino acids. Asp, Glu Val, Leu, Ile Ala, Ser, Gly Phe, Trp. Choose essential amino acids. Asp, Glu Val, Leu, Ile Ala, Ser, Gly Phe, Trp. Essential amino acids. „10“. branched chain: Val, Leu, Ile - PowerPoint PPT Presentation
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Metabolism of amino acids
- exercise -
Vladimíra Kvasnicová
Choose essential amino acids
a) Asp, Glu
b) Val, Leu, Ile
c) Ala, Ser, Gly
d) Phe, Trp
Choose essential amino acids
a) Asp, Glu
b) Val, Leu, Ile
c) Ala, Ser, Gly
d) Phe, Trp
Essential amino acids
1) branched chain: Val, Leu, Ile
2) basic: His, Arg, Lys
3) aromatic: Phe (→ Tyr), Trp
4) sulfur-containing: Met (→ Cys)
5) other: Thr
„10“
Choose amino acids from which the other amino acid can be synthesized in a human body
a) valine → leucine
b) aspartate → asparagine
c) phenylalanine → tyrosine
d) methionine + serine → cysteine
Choose amino acids from which the other amino acid can be synthesized in a human body
a) valine → leucine leucine is the essential AA
b) aspartate → asparagine
c) phenylalanine → tyrosine
d) methionine + serine → cysteine
Synthesis of
ASPARAGINE
needs glutamine as
–NH2 group donor
(it is not ammonia as in the Gln synthesis)
The figure was adopted from Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley‑Liss, Inc., New York, 1997. ISBN 0‑471‑15451‑2
The figure is from http://web.indstate.edu/thcme/mwking/amino-acid-metabolism.html (Jan 2007)
Synthesis of Tyr from Phe
The figure is from http://web.indstate.edu/thcme/mwking/amino-acid-metabolism.html (Jan 2007)
Synthesis of Cys from Met and Ser
The amino acids can be formed from the citrate cycle
intermediatesin a human body
a) a-ketoglutarate → glutamate
b) succinyl-CoA → isoleucine
c) oxaloacetate → aspartate
d) malate → threonine
The amino acids can be formed from the citrate cycle
intermediatesin a human body
a) a-ketoglutarate → glutamate
b) succinyl-CoA → isoleucine Ile is the essential AA
c) oxaloacetate → aspartate
d) malate → threonine Thr is the essential AA
The figure is from http://www.tcd.ie/Biochemistry/IUBMB-Nicholson/gif/13.html (Dec 2006)
Amphibolic character
of citrate cycle
The compound(s) can be synthesized from the amino acid
a) tyrosine → serotonin
b) serine → ethanolamine
c) tryptophan → catecholamines
d) cysteine → taurine
The compound(s) can be synthesized from the amino acid
a) tyrosine → serotonin Tyr → catecholamines
b) serine → ethanolamine formed by decarboxylation
c) tryptophan → catecholamines Trp → serotonin
d) cysteine → taurine
The figure was adopted from Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley‑Liss, Inc., New York, 1997. ISBN 0‑471‑15451‑2
taurin is used in conjugation reactions in the liver
– it is bound to hydrophobic substances to increase their solubility
(e.g. conjugation of bile acids)
If the amino acid is metabolised the substance is formed:
a) methionine gives homocysteine
b) serine gives glycine and folic acid derivative: methylene tetrahydrofolate
c) glutamine releases ammonia
d) some amino acides can be degraded to acetoacetate
If the amino acid is metabolised the substance is formed:
a) methionine gives homocysteine
b) serine gives glycine and folic acid derivative: methylene tetrahydrofolate
c) glutamine releases ammonia
d) some amino acides can be degraded to acetoacetate = one of ketone bodies
The figure is from http://web.indstate.edu/thcme/mwking/amino-acid-metabolism.html (Jan 2007)
B12
Regeneration of Met
(vitamins: folate+B12)
The figure is from http://www.biocarta.com/pathfiles/GlycinePathway.asp (Jan 2007)
Synthesis of serine and glycine
glycolysis
Choose products of the transamination reactions
a) alanine → pyruvate
b) glutamate → 2-oxoglutarate
c) aspartate → oxaloacetate
d) phenylalanine → tyrosine
Choose products of the transamination reactions
a) alanine → pyruvate
b) glutamate → 2-oxoglutarate
c) aspartate → oxaloacetate
d) phenylalanine → tyrosine it is not transamination
The figure is from http://web.indstate.edu/thcme/mwking/nitrogen-metabolism.html (Jan 2007)
Transamination reaction
! REVERSIBLE !
enzymes: amino transferases
coenzyme: pyridoxal phosphate (vit. B6 derivative)
The figure was adopted from Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley‑Liss, Inc., New York, 1997. ISBN 0‑471‑15451‑2
alanine aminotransferase
(ALT = GPT)
aspartate aminotransferase
(AST = GOT)
Amino transferases important in medicine („transaminases“)
Amino nitrogen released from carbon sceletons of AAs can be transported in
blood as
a) NH4+
b) alanine
c) glutamine
d) urea
Amino nitrogen released from carbon sceletons of AAs can be transported in
blood as
a) NH4+ physiologically up to 35 µmol/l (NH3 + H + NH4
+)
b) alanine formed by transamination from pyruvate
c) glutamine the most important transport form of –NH2
d) urea it is the end product of degradation of amino nitrogen (liver → kidneys → urine)
Transport of amino nitrogen
from degraded muscle proteins
productsexcreted
with urine
The figure was adopted from Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley‑Liss,
Inc., New York, 1997. ISBN 0‑471‑15451‑2
Glucose-alanine cycle
The figure was adopted from Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley‑Liss, Inc., New York, 1997. ISBN 0‑471‑15451‑2
alanine transfers both the carbon
sceleton for gluconeogenesis and –NH2 group
glutamine synthetase
GLUTAMINE
= the most important transport form af amino nitrogen in
blood
it transfers two amino groups released by degradation of AAs
The figure was adopted from Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley‑Liss, Inc., New York, 1997. ISBN 0‑471‑15451‑2
Choose glucogenic amino acids
a) alanine
b) lysine
c) leucine
d) glutamine
Choose glucogenic amino acids
a) alanine
b) lysine
c) leucine
d) glutamine
7 degradation products of AAs
1. pyruvate Gly, Ala, Ser, Thr, Cys, Trp
2. oxaloacetate Asp, Asn
3. a-ketoglutarate Glu, Gln, Pro, Arg, His
4. succinyl-CoA Val, Ile, Met, Thr
5. fumarate Phe, Tyr
6. acetyl-CoA Ile
7. acetoacetyl-CoA Lys, Leu, Phe, Tyr, Trp
glucogenic AAs
ketogenic AAs
Glutamate dehydrogenase (GMD)
a) catalyzes conversion of Glu to oxaloacetate
b) is found in mitochondria of hepatocytes
c) produces ammonia
d) needs pyridoxal phosphate as a coenzyme
Glutamate dehydrogenase (GMD)
a) catalyzes conversion of Glu to oxaloacetate
b) is found in mitochondria of hepatocytes
c) produces ammonia
d) needs pyridoxal phosphate as a coenzyme
The figure is from http://web.indstate.edu/thcme/mwking/nitrogen-metabolism.html (Jan 2007)
GLUTAMATE DEHYDROGENASE
removes amino group from carbon sceleton of Glu in the liver
1. –NH2 from AAs was transfered by transamination → Glu
2. free ammonia is released by oxidative deamination of Glu
Choose correct statement(s) about metabolism of amino acids
a) alanine aminotransferase (ALT) transforms pyruvate to alanine
b) aspartate aminotransferase (AST) transforms aspartate to a-ketoglutarate
c) glutamine synthetase transforms glutamate to glutamine
d) glutaminase catylyzes conversion of glutamine to ammonia and a-ketoglutarate
Choose correct statement(s) about metabolism of amino acids
a) alanine aminotransferase (ALT) transforms pyruvate to alanine
b) aspartate aminotransferase (AST) transforms aspartate to a-ketoglutarate
c) glutamine synthetase transforms glutamate to glutamine
d) glutaminase catylyzes conversion of glutamine to ammonia and a-ketoglutarate
The figure was adopted from Devlin, T. M. (editor): Textbook of Biochemistry with Clinical Correlations, 4th ed. Wiley‑Liss, Inc., New York, 1997. ISBN 0‑471‑15451‑2
alanine aminotransferase
(ALT = GPT)
aspartate aminotransferase
(AST = GOT)
Amino transferases important in medicine („transaminases“)
Glutamine is principaltransport form of amino nitrogen
The figure is from http://www.sbuniv.edu/~ggray/CHE3364/b1c25out.html (Dec 2006)
The amino acids can enter the citrate cycle as the molecules
a) alanine → → acetyl-CoA
b) aspartate → oxaloacetate
c) valine → → succinyl-CoA
d) glutamine → → a-ketoglutarate
The amino acids can enter the citrate cycle as the molecules
a) alanine → → acetyl-CoA
b) aspartate → oxaloacetate
c) valine → → succinyl-CoA
d) glutamine → → a-ketoglutarate
The figure is from http://www.biocarta.com/pathfiles/glucogenicPathway.asp (Jan 2007)
The entrance of amino acids into the citrate cycle
Ornithine cycle
a) proceeds only in the liver
b) produces uric acid
c) includes arginine as an intermediate
d) produces energy in a form of ATP
Ornithine cycle
a) proceeds only in the liver
b) produces uric acid
c) includes arginine as an intermediate
d) produces energy in a form of ATP
The figure is from http://www.biocarta.com/pathfiles/ureacyclePathway.asp (Jan 2007)
Detoxication of ammonia in the liver
The figure is from http://courses.cm.utexas.edu/archive/Spring2002/CH339K/Robertus/overheads-3/ch18_TCA-Urea_link.jpg
(Jan 2007)
Interconnection of the urea cycle with the citrate cycle
In the urea synthesis
a) ammonia reacts with ornithine → citrulline
b) carbamoyl phosphate synthetase I (= mitochondrial) regulates the cycle
c) aspartate is used as a –NH2 group donor
d) urea is formed – it can be used as an energy substrate for extrahepatic tissues
In the urea synthesis
a) ammonia reacts with ornithine → citrulline
b) carbamoyl phosphate synthetase I (= mitochondrial) regulates the cycle
c) aspartate is used as a –NH2 group donor
d) urea is formed – it can be used as an energy substrate for extrahepatic tissues
regulatory enzyme activation inhibition
carbamoyl phosphatesynthetase I(= mitochondrial)
N-acetylglutamate
N-acetylglutamatesynthetase
arginine
Regulation of urea cycle
allosteric regulation + enzyme induction by protein rich diet or by metabolic changes during starvation
Urea synthesis is inhibited by acidosis– HCO3
- is saved