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Metabolism of amino acids- exercise -
Vladimíra Kvasnicová
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Choose essential amino acids
a) Asp, Glu
b) Val, Leu, Ile
c) Ala, Ser, Gly
d) Phe, Trp
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Choose essential amino acids
a) Asp, Glu
b) Val, Leu, Ile
c) Ala, Ser, Gly
d) Phe, Trp
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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“
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Choose amino acids from which the
other amino acid can be synthesized ina human body
a) valine → leucine
b) aspartate → asparagine
c) phenylalanine → tyrosine
d) methionine + serine → cysteine
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Choose amino acids from which the
other amino acid can be synthesized ina human body
a) valine → leucine leucine is the essential AA
b) aspartate → asparagine
c) phenylalanine → tyrosine
d) methionine + serine → cysteine
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Synthesis of
ASPARAGINE
needs glutamine as–NH
2group 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
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The figure is from http://web.indstate.edu/thcme/mwking/amino-acid-metabolism.html (Jan 2007)
Synthesis of Tyr from Phe
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The figure is from http://web.indstate.edu/thcme/mwking/amino-acid-metabolism.html (Jan 2007)
Synthesis of Cys from Met and Ser
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The amino acids can be formed from thecitrate cycle intermediates
in a human body
a) αααα-ketoglutarate → glutamate
b) succinyl-CoA → isoleucine
c) oxaloacetate → aspartate
d) malate → threonine
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The amino acids can be formed from
the citrate cycle intermediatesin a human body
a) αααα-ketoglutarate → glutamate
b) succinyl-CoA → isoleucine Ile is the essential AA
c) oxaloacetate → aspartate
d) malate → threonine Thr is the essential AA
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The figure is from http://www.tcd.ie/Biochemistry/IUBMB-Nicholson/gif/13.html (Dec 2006)
Amphibolic
characterof citrate cycle
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The compound(s) can be synthesizedfrom the amino acid
a) tyrosine → serotonin
b) serine → ethanolamine
c) tryptophan → catecholamines
d) cysteine → taurine
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The compound(s) can be synthesizedfrom the amino acid
a) tyrosine → serotonin Tyr → catecholamines
b) serine → ethanolamine formed by decarboxylation
c) tryptophan → catecholamines Trp → serotonin
d) cysteine → taurine
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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)
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If the amino acid is metabolised the
substance is formed:
a) methionine gives homocysteine
b) serine gives glycine and folic acidderivative: methylene tetrahydrofolate
c) glutamine releases ammonia
d) some amino acides can be degraded toacetoacetate
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If the amino acid is metabolised the
substance is formed:
a) methionine gives homocysteine
b) serine gives glycine and folic acidderivative: methylene tetrahydrofolate
c) glutamine releases ammonia
d) some amino acides can be degraded toacetoacetate = one of ketone bodies
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The figure is from http://web.indstate.edu/thcme/mwking/amino-acid-metabolism.html (Jan 2007)
B12
Regeneration of
Met(vitamins: folate+B
12)
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The figure is from http://www.biocarta.com/pathfiles/GlycinePathway.asp (Jan 2007)
Synthesis of serine and glycineglycolysis
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Choose products of the transamination
reactions
a) alanine → pyruvate
b) glutamate → 2-oxoglutarate
c) aspartate → oxaloacetate
d) phenylalanine → tyrosine
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Choose products of the transamination
reactions
a) alanine → pyruvate
b) glutamate → 2-oxoglutarate
c) aspartate → oxaloacetate
d) phenylalanine → tyrosine it is not transamination
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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)
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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“)
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Amino nitrogen released from carbon
skeletons of AAs can be transported inblood as
a) NH4+
b) alanine
c) glutamine
d) urea
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Amino nitrogen released from carbon
skeletons of AAs can be transported inblood as
a) NH4+ physiologically up to 35 mol/l (NH
3+ H +
↔ NH4+)
b) alanine formed by transamination from pyruvate
c) glutamine the most important transport form of –NH 2
d) urea it is the end product of degradation of amino nitrogen (liver → kidneys → urine)
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Transport ofamino nitrogen
from degraded muscle proteins
products excreted 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
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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 transfersboth the carbon
skeleton forgluconeogenesisand –NH
2group
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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
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Choose glucogenic amino acids
a) alanine
b) lysine
c) leucine
d) glutamine
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Choose glucogenic amino acids
a) alanine
b) lysine
c) leucine
d) glutamine
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7 degradation products of AAs
1. pyruvate ←←←← Gly, Ala, Ser, Thr, Cys, Trp
2. oxaloacetate ←←←← Asp, Asn
3. αααα-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
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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
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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
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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→ Glu2. free ammonia is released by oxidative deamination of Glu
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Choose correct statement(s) about
metabolism of amino acids
a) alanine aminotransferase (ALT) transforms
pyruvate to alanine
b) aspartate aminotransferase (AST) transforms
aspartate to αααα-ketoglutarate
c) glutamine synthetase transforms glutamate to
glutamined) glutaminase catylyzes conversion of glutamine
to ammonia and αααα-ketoglutarate
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Choose correct statement(s) about
metabolism of amino acids
a) alanine aminotransferase (ALT) transforms
pyruvate to alanine
b) aspartate aminotransferase (AST)
transforms aspartate to αααα-ketoglutarate
c) glutamine synthetase transforms glutamateto glutamine
d) glutaminase catylyzes conversion ofglutamine to ammonia and αααα-ketoglutarate
A i f i i di i
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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 principal
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Glutamine is principaltransport form of amino nitrogen
The figure is from http://www.sbuniv.edu/~ggray/CHE3364/b1c25out.html (Dec 2006)
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The amino acids can enter the citrate
cycle as the molecules
a) alanine →→ acetyl-CoA
b) aspartate → oxaloacetate
c) valine →→ succinyl-CoA
d) glutamine →→ αααα-ketoglutarate
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The amino acids can enter the citrate
cycle as the molecules
a) alanine →→ acetyl-CoA
b) aspartate → oxaloacetate
c) valine →→ succinyl-CoA
d) glutamine →→ αααα-ketoglutarate
Th t f i id i t th it t l
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The figure is from http://www.biocarta.com/pathfiles/glucogenicPathway.asp (Jan 2007)
The entrance of amino acids into the citrate cycle
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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
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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
D f h l
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The figure is from http://www.biocarta.com/pathfiles/ureacyclePathway.asp (Jan 2007)
Detoxication of ammonia in the liver
Interconnection of the urea cycle with the
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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 thecitrate cycle
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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 energysubstrate for extrahepatic tissues
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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 energysubstrate for extrahepatic tissues
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• arginineN-acetylglutamate
synthetase
• N-acetylglutamatecarbamoyl phosphatesynthetase I(= mitochondrial)
inhibition activation regulatory enzyme
Regulation of urea cycle
allosteric regulation + enzyme induction by protein rich diet or by metabolic changes during starvation
Urea synthesis is inhibited by acidosis
– HCO 3 -
is saved