Biochemistry-7-1-AA 1
Metabolism of AA
Biochemistry-7-1-AA 2
Metabolism of proteins Sources of AA:
a) Exogenic proteins- food
b) Endogenic proteins
c) AA biosynthesis of nonesential AA
Biochemistry-7-1-AA 3
AA pool
Sources:
1) Proteolysis of exogenic proteins from food
2) Proteolysis of tissue proteins
3) Synthesis of nonesential AA
Using of pool of AA:
1) Synthesis of plasmatic and tissue protiens
2) Synthesis of specific. N compounds
3) Deamination + utilisation of C scelet
Using of C scelet of AA:
1) Gluconeogenesis
2) Synthesis of FA and TAG
3) Metabolic fuel = oxidation in CAC to CO2 = profit of energy
Biochemistry-7-1-AA 4
Degradation of proteins
Exogenic protiens – in lumen GIT, proenzyme
Stomach (pepsin, pepsinogen, activation by HCl
Intestine - trypsin, chymotripsin, elastase, karboxypeptidase, aminopeptidase
ect.
Endogennic proteins in cells = intercelular degradation of proteins:
a) lysozome , b) ubiqitin-proteasome
Biochemistry-7-1-AA 5
Degradation of proteins
Exogenic proteins
 Lumen GIT
 stomach – pepsin
 intestine – pankreatic
proteasis (trypsin,
chymotrypsin ect.)
Endogenní proteiny
 Intracelular proteasis
 Two systems:
1. Lyzosome
2. Ubiqitin-proteasome
Biochemistry-7-1-AA 6
pepsine
trypsine
pepsinogen
(activation by
HCl)
karboxypeptidase
aminopeptidase
AA – resorption
to portal vein
pH 1-2
chymotrypsin, elastasa
Digestion of exogenic proteins
Enzymes in GIT
Biochemistry-7-1-AA 7
Endogenic proteins with different biological time life
Protein Time life
Ornithindekarboxylase
RNA polymerasa I
Prealbumin
Laktátdehydrogenase
Albumin
IgG
Kolagen
Elastin
12 min
1,3 hor
2 days
4 days
19 days
23 days
years
Whole life (?)
Biochemistry-7-1-AA 8
Lysozoms
 Degradation of proteins
 Independent on ATP
 Nonspecific
 Extracellular
 endocellular
Biochemistry-7-1-AA 9
Degradation of endogenic proteins in
lysosoms
 Independent on ATP, nonspecific
 Extracelular and membrane proteins
 Proteins with long half-life
 Extracelular glycoproteins (firt digestion
of sialic acids)
Biochemistry-7-1-AA 10
Lyzosomal hydrolase cleave bond formed by condensation
Hydrolase Type of bond
Glucosidase
Galactosidase
Hyaluronidase
Arylsulfatase
Lysozym
Kathepsin
Kolagenase
Elastase
Ribonuclease
Lipase
Fosfatase
Ceramidase
glykosid
glykosid
glykosid
sulphoester
glykosid
peptid
peptid
peptid
phosphodiester
ester
phosphoester
Amid
Biochemistry-7-1-AA 11
Ubiqitin (UB) –labelled proteins for degradation in
proteasome
 Small proteins in al cells
 C-terminus of UB bind to Lys of proteins - „kiss of death“
 Bnding of UB to proteins 3 phases -3 enzymes E1, E2 a E3
 Binding of UB to E1-SH require ATP
 UB - polyubiquitination
 Marked protiens is degradated in proteasome
Biochemistry-7-1-AA 12
Labelling of proteins by
UB
E1 enzyme activated UB by ATP
E2 ubikvitin conjugation enzyme
E3 ubiqitin-protein ligase
Biochemistry-7-1-AA 13
Proteasome
 proteasome most exclusively used in mammals is the cytosolic
26S proteasome, which is about 2000 kilodaltons (kDa) in
molecular mass containing one 20S protein subunit and two 19S
regulatory cap subunits.
 The core is hollow and provides an enclosed cavity in which
proteins are degraded; openings at the two ends of the core
allow the target protein to enter.
 Each end of the core particle associates with a 19S regulatory
subunit that contains multiple ATPase active sites and ubiquitin
binding sites; it is this structure that recognizes polyubiquitinated
proteins and transfers them to the catalytic core.
Biochemistry-7-1-AA 14
Proteasome- degradation of proteins with short half-life,
cyclins and other regulation proteins, transcription factors ,
damaged and misfolded proteins
UB + short peptides
Protein-UB
AK
cytosol
peptidase
Biochemistry-7-1-AA 15
3D structure of proteasome
28 homolog subunits
Active sites - yellow
Biochemistry-7-1-AA 16
Bortezomib is inhibitor proteasome atom
bor –catalitic site (Thr)
(myeloma)
Syntetic tripeptid:
COOH –boric acid
Biochemistry-7-1-AA 17
Caspase proteolytic cascade
 cysteine-aspartic proteases or cysteine-dependent aspartatedirected
proteases are a family of cysteine proteases that play
essential roles in apoptosis (programmed cell death), necrosis,
and inflammation.[2]
 Caspases are essential in cells for apoptosis, or programmed cell
death, in development and most other stages of adult life, and
have been termed "executioner" proteins for their roles in the
cell.
 Some caspases are also required in the immune system for the
maturation of lymphocytes. Failure of apoptosis is one of the
main contributions to tumour development and autoimmune
diseases; this, coupled with the unwanted apoptosis that occurs
with ischemia or Alzheimer's disease, has stimulated interest in
caspases as potential therapeutic targets since they were
discovered in the mid-1990s.
Biochemistry-7-1-AA 18
Biological value BV
 is a measure of the proportion of absorbed protein from a food which becomes
incorporated into the proteins of the organism's body.
 It summarises how readily the broken down protein can be used in protein synthesis in the
cells of the organism. Proteins are the major source of nitrogen in food, unlike
carbohydrates and fats. This method assumes protein is the only source of nitrogen and
measures the proportion of this nitrogen absorbed by the body which is then excreted. The
remainder must have been incorporated into the proteins of the organisms body. A ratio of
nitrogen incorporated into the body over nitrogen absorbed gives a measure of protein
'usability' - the BV.
 Unlike some measures of protein usability, biological value does not take into account how
readily the protein can be digested and absorbed (largely by the small intestine). This is
reflected in the experimental methods used to determine BV.
 BV uses two similar scales:
 The true percentage utilization (usually shown with a percent symbol).
 The percentage utilization relative to a readily utilizable protein source, often egg (usually
shown as unitless).
 These two values will be similar but not identical.
 The BV of a food varies greatly, and depends on a wide variety of factors. In particular the
BV value of a food varies depending on its preparation and the recent diet of the organism.
This makes reliable determination of BV difficult and of limited use — fasting prior to testing
is universally required in order to make the values reliable.
 BV is commonly used in nutrition science in many mammalian organisms, and is a relevant
measure in humans.[1] It is a popular guideline in bodybuilding in protein choice.[2][3]
Biochemistry-7-1-AA 19
Esencial and semiesencial AA
 valin
 leucin
 isoleucin
 threonin
 phenylalanin
 tryptofan
 lysin
 methionin
Semiesencial AA
• histidin, arginin -growth
• alanin, glutamin, taurin - stress
• cca 30 % met -cys
• cca 50 % phe - tyr
Biochemistry-7-1-AA 20
P
O
O
OH
OHH2N
O
carbamoyl phosphate
COO-
C
R
O
CO2
-
C
CH2
O
CO2
-
Biochemistry-7-1-AA 21
Proteins
NH3
glutamate
glutamate + urea
(excretion-urine)
2-oxoglutarate +
glutamin
proteolysis
dehydrogenation + deamination
Detoxication in lung
Deamidation
in
kidney
AA
TA
Detoxification in
other tissues
NH4
+
(excretion in urine)
NH4
+
(excretion-urine)
deamination
kidney
Catabolic pathway of AA/N
Biochemistry-7-1-AA 22
3 Stages of AA Breakdown
1. Deamination: Amino group is converted to ammonia or
transferred to form Asp
2. Incorporation of N from Asp and NH3
+ into urea
3. Conversion of AA carbons into metabolic
intermediates
H2N
O
NH2
urea
Biochemistry-7-1-AA 23
Transamination
transport -NH2 group from 1 substrate to other
 Most of AA (no Lys, Thr, Pro, His, Trp, Arg, Met)
 Amino group- transport to keto group (2-oxo acid)
(most 2-oxoglutarate)
 cofactor - pyridoxalphosphate – Schiff base
 reversible reaction  synthesis of AA
Biochemistry-7-1-AA 24
General equation of transamination reaction
CH2CH2COOH
O
CHOOC+R CH
NH2
COOH
Amino acid 2-oxoglutarate
HOOC CH CH2CH2COOH
NH2
+R C
O
COOH
glutamate2-oxo acid
aminotransferase
pyridoxalphosphate
Biochemistry-7-1-AA 25
Pyridoxalphosphate transfer -NH2 from AA to 2-oxo
glutarate
enzym
kofaktor
N
CH2O
H3C
HO
C
OH
P
O
O
O
Reactive group
cofactor
Enzyme-
covalent
bond,
apoenzyme
Lys
Biochemistry-7-1-AA 26
1. phase transamination AA  oxo acid
pyridoxal-P  pyridoxamin-P
Schiff base
CH
NH2
COOHR R C COOH
CH2
N
R CH COOH
CH
N H2O
R C
O
COOH
CH2NH2
C
OH - H2O
AA
pyridoxamin-Ppyridoxal-P Imino acid
Oxo acid
izomeration
aldimin pyridoxal ketimin oxo A
Biochemistry-7-1-AA 27
2. phase transamination 2-oxoglutarate  glutamate
pyridoxamin-P  pyridoxal-P
2-oxoglutarate glutamate
pyridoxamin-P
pyridoxal-P
C
OH
CH2NH2
- H2O
H2O
CH2
CH2
COOH
CHOOC
O
CH2
CH2
COOH
CHOOC
N
CH2
ketimin
oxoA
CH2
CH2
COOH
CHHOOC
N
CH
aldimin
pyridoxal
CH2
CH2
COOH
CHHOOC
NH2
Biochemistry-7-1-AA 28
The transaminase enzymes
 are important in the production of various amino acids, and measuring the
concentrations of various transaminases in the blood is important in the
diagnosing and tracking many diseases. Transaminases require the coenzyme
pyridoxal-phosphate, which is converted into pyridoxamine in the first phase of
the reaction, when an amino acid is converted into a keto acid. Enzyme-bound
pyridoxamine in turn reacts with pyruvate, oxaloacetate, or alpha-ketoglutarate,
giving alanine, aspartic acid, or glutamic acid, respectively. Many transamination
reactions occur in tissues, catalysed by transaminases specific for a particular
amino/keto acid pair. The reactions are readily reversible, the direction being
determined by which of the reactants are in excess. The specific enzymes are
named from one of the reactant pairs, for example; the reaction between
glutamic acid and pyruvic acid to make alpha ketoglutaric acid and alanine is
called glutamic-pyruvic transaminase or GPT for short.
 Tissue transaminase activities can be investigated by incubating a homogenate
with various amino/keto acid pairs. Transamination is demonstrated if the
corresponding new amino acid and keto acid are formed, as revealed by paper
chromatography. Reversibility is demonstrated by using the complementary
keto/amino acid pair as starting reactants. After chromatogram has been taken
out of the solvent the chromatogram is then treated with ninhydrin to locate the
spots.
 Two important transaminase enzymes are AST (SGOT) and ALT (SGPT), the
presence of elevated transaminases can be an indicator of liver damage. This
discovery was made by Fernando De Ritis, Mario Coltorti and Giuseppe Giusti
in 1955 at the University of Naples.[1][2][3]
Biochemistry-7-1-AA 29
N of the most of AAs –transamination
to glutamate
Deamination associated with
dehydrogenation of Glutamate
Biochemistry-7-1-AA 30
Glutamic acid (abbreviated as Glu or E) is one of the 20-22 proteinogenic
amino acids, and its codons are GAA and GAG. It is a non-essential amino
acid. The carboxylate anions and salts of glutamic acid are known as
glutamates. In neuroscience, glutamate is an important neurotransmitter
that plays a key role in long-term potentiation and is important for learning
and memory.[4]
Biochemistry-7-1-AA 31
Deamination associated with dehydrogenation of
Glutamate is reversible
NAD(P)+
hlavní zdroj
amoniaku
v buňkách
HOOC CH CH2CH2COOH
NH2
CH2CH2COOH
NH
CHOOC
- 2H
H2O
L-glutamate 2-iminoglutarate
2-oxoglutrate
NH3 CH2CH2COOH
O
CHOOC+
GMD
Mail source
of ammonia
in cells
Biochemistry-7-1-AA 32
Glutamate dehydrogenase (GMD, GD, GDH)
 cofactor NAD(P)+
 GMD is reversible, dehydrogenation NAD+,
hydrogenation NADPH+H+
 2 steps:
 dehydrogenation >CH-NH2 imino group >C=NH
 hydrolysis iminogroup to oxo group and NH3
Biochemistry-7-1-AA 33
Cell localisation of AA transformation
transamination (ALT)  glutamate
NH3
glutamate
Synthesis of urea
mitochondria
cytosol
GMD
Glu + NH3  Gln transamination
(AST)
cytosol
Biochemistry-7-1-AA 34
 Dehydrogenation deamination of glutamate
in cells of many tissues
 Bacterial degradation of proteins in large intestine
NH3 difusion to vena portae blood  high
concetration of NH3  remove by liver
2 sources of NH3 in organism
Biochemistry-7-1-AA 35
Other sources of NH3 from other substrates
 Deamination of adenine
 Oxidation deamination of AA (H2O2)
 Desaturation of His
 Oxidation deamination of Lys
 Dehydratation deamination of Ser
 Oxidation deamination of biogenic amines
Biochemistry-7-1-AA 36
Deamination of adenine
N
N
N
N
NH2
Rib P
N
N
N
N
OH
Rib P
H2O
+ NH3
adenosinemonoP inosinemonoP
Biochemistry-7-1-AA 37
Oxidation deamination of some AA
• glycin
• degradation of D-AA
• side product H2O2
H2O + ½ O2
R CH
NH2
COOH
FAD FADH2
R C COOH
NH
O2H2O2
katalase
H2O
R C COOH
O
NH3
iminoacid
Biochemistry-7-1-AA 38
Oxidation deamination of biogennic amines
R-COOH
acid
R CH2 NH2
FAD FADH2
H2O2 O2
R CH NH
H2O
R CH O
NH3
Biogenic amine imine aldehyde
monoaminoxidase
Biochemistry-7-1-AA 39
Desaturation -deamination of His
 No transamination
 Histidine catabolism begins with release of the α-amino group
catalyzed by histidase,
 introducing a double bond into the molecule.
 As a result, the deaminated product, urocanate, is not the usual αketo
acid associated with loss of α-amino nitrogens. The end
product of histidine catabolism is glutamate, making histidine one of
the glucogenic amino acids.
CH CH
NH2
COOH
H
N
N
H
CH CH COOH
N
N
H
- NH3
Urocanate
Urocanic acid
Biochemistry-7-1-AA 40
 noenzymatic carbamylation of proteins (high concetration of urea
in cells) í.
Prot-NH2 + NH2-CO-NH2  NH3 + Prot-NH-CO-NH2
 catabolismus pyrimidin base
cytosin/uracil  NH3 + CO2 + β-alanin
thymin  NH3 + CO2 + β-aminoisobutyrate
 Synthesis of hem (4 porfobilinogen  4 NH3 + uroporfyrinogen)
Other reaction with production of
NH3
Biochemistry-7-1-AA 41
Hydrolysis of amid group of Gln in kidney NH4
+ - urine
(deamidation)
Glutamine- non toxic form of NH3
glutaminase
COOH
CH
CH2
H2N
CH2
C
O NH2
H2O
COOH
CH
CH2
H2N
CH2
C
O OH
+ NH3
glutamine glutamate
Biochemistry-7-1-AA 42
Patology- production of NH3
 Bleeding to GIT  higher NH3 in blood
 uroinfection – bacterial urease –catalysis of hydrolysis of urea
H2N-CO-NH2 + H2O  2 NH3 + CO2
NH3 + H2O  NH4
+ + OHAlcalic
urine (pH 8)  phosphate concrements
Biochemistry-7-1-AA 43
Acidobazic properties of NH3
pKB (NH3) = 4,75 (weak base)
NH3 + H2O  NH4
+ + OHpKA
(NH4
+) = 14 - 4,75 = 9,25 (very weak acid)
At physiological pH ICT and ECT (7,40) :
98 % NH4
+
2 % NH3
Biochemistry-7-1-AA 44
NH4
+ in body liquid
Body liquid
conc. NH4
+
(mmol/l)
Metabolic origin of NH4
+
urine
Saliva
Portal blood
Venous blood
10 – 40
2 – 3
0,1 – 0,3
< 0,03
deamidation Gln + deamition Glu in kidney
Hydrolysis of urine in mouth microbe
Decompose of proteins in large intestine,
catabolismu Gln/Glu in enterocyte
Catabolism of AA in tissues
Biochemistry-7-1-AA 45
důležité při jaterním selhávání
1. nízkoproteinová dieta
2. alterace střevní mikroflóry
 probiotika – živé mikrorganismy, podporují kvasné procesy na úkor
hnilobných (laktobacily, bifidobakterie) – kefír, acidofilní mléko ...
 prebiotika – nestravitelné složky potravy, které selektivně stimulují
růst probiotik (oligofruktosa, inulin, vláknina)
 střevní antibiotika – lokálně působící (neomycin, metronidazol),
krajní řešení, krátkodobé
Jak omezit vznik amoniaku v lidském těle?
Biochemistry-7-1-AA 46
 Detoxification of NH3
 3 ways:
 1) in urea cycle
 2) formation of glutamine
 3) formation of glutamate
Biochemistry-7-1-AA 47
3 products of detoxification of NH3
Characteristic Urea Glutamine Glutamate
importance
Type of componds
Reaction of synthesis
Enzyme
energy need
Cell localisation
Organ

diamide H2CO3
ureosynt. cycl
5 enzymes
3 ATP
mitoch. + cytosol
Only liver

γ-amid Glu
Glu + NH3
Gln-syntetase
1 ATP
Mitoch.
liver, others

α-amino acid
red. amination 2-OG
GMD
1 NADPH+H+
Mitoch.
(CNS)
Biochemistry-7-1-AA 48
Production of Urea
 Organisms can excrete excess N as
 Ammonia (ammonotelic; e.g., aquatic animals)
 Urea (ureotelic; terrestrial animals)
 Synthesized in liver by urea cycle (discovered by Hans Krebs,
before he elucidated the TCA)
 Uric acid (uricotelic: birds, reptiles, dinosaurs?)
NH
ON
H
N
H
O
H
N
O
uric acid
Biochemistry-7-1-AA 49
Synthesis of urea in
liver
2 reaction in mitochondria
Other reactions in cytosol
Biochemistry-7-1-AA 50
NH3
CO2
2ATP
2ADP + P
O
C
O P
NH2
COOH
NH2 CH2
CH2
CH2
CH NH2
OH2
HOOC CH2 CH
NH2
COOH
O
NH2 C NH CH2
CH2
CH2
CH
COOH
NH2
NHCOOH
CH NH C NH CH2
CH2
CH2
CH NH2
COOH
CH2
COOH
HOOC
HC
CH
COOH
NH
NH2 C NH CH2
CH2
CH2
CH
COOH
NH2
OH2
O
C
NH2 NH2
fumarate
arginine
urea
ornithine
citrulline
aspartate
argininesuccinate
Carbamoyl phosphate
MATRIX
MITOCHONDRIA
CYTOPLAZM
Biochemistry-7-1-AA 51
1. Carbamoylphosphate synthesis (matrix)
CO2 NH4
+
+
2 ATP 2 ADP + 1 P
H2N O
C
O
P
O
O
O
 carbamoylphsphatsynthetase, alloster. activator N-
acetylglutamate
 matrix mitochondria
 2 mols ATP
 Amid bond + hybrid anhydrid
 Macroergic compound
Biochemistry-7-1-AA 52
Carbamoyl is acyl carbamic acid
H2N
C
O
OH H2N
C
O
Acid carbamic
monoamid H2CO3
hypotetic
carbamoyl
Biochemistry-7-1-AA 53
2. Citrulline formation (matrix)
CH2CH2CH2CHCOOH
NH2 NH2
H2N O
C
O
P
O
O
O
CH2CH2CH2CHCOOH
NH NH2
C
NH2
O
HO P
O
O
O
citruline
ornitine
carbamoyl
Biochemistry-7-1-AA 54
3. Argininosuccinate formation, NH2 in Asn (cytosol)
citruline
CH2CH2CH2CHCOOH
NH NH2
C
NH2
O
CHCOOH
CH2COOH
H2N
aspartate
CH2CH2CH2CHCOOH
NH NH2
C
NH2
N CHCOOH
CH2COOH
H2O-
argininosuccinate
ATP
AMP + PP
Biochemistry-7-1-AA 55
4. Cleavage of argininosuccinate
CH2CH2CH2CHCOOH
NH NH2
C
NH2
N CHCOOH
CH2COOH
argininosuccinate
CH2CH2CH2CHCOOH
NH NH2
C
NH2
N H
arginine
C
C
COOH
H
H
HOOC
fumarate
Biochemistry-7-1-AA 56
5. Hydrolysis of arginine gives urea
CH2CH2CH2CHCOOH
NH NH2
C
NH2
N H
arginine
H2O
CH2CH2CH2CHCOOH
NH2
NH2
O
C
NH2
NH2
ornitine
urea
Biochemistry-7-1-AA 57
H2N
C
O
NH2
Free NH3 aspartate
Metabolic origin of N in urea molecule
Biochemistry-7-1-AA 58
CO2 + NH4
+ + aspartate  urea + fumarate + H2O + 2 H+
CO(NH2)2 + -OOC-CH=CH-COO- + H2O + 2 H+
Synthesis of urea in proton-productive action
OOC CH
NH3
CH2 COO
CO2 + NH4
+ +
Biochemistry-7-1-AA 59
Urea is not electrolyt
 Polar substance  very well soluble in water
 Very well transported –membrane (hydrophilic canal)
 Osmolarity of blood plasma:
osmolarity  2 [Na+] + [glukose] + [urea] mmol/kg H2O
 In liver
 Excreted by urine – dependent on amount of proteins
 330-600 mmol/d (20-35 g/d)
Biochemistry-7-1-AA 60
Urea in blood plasma(2-8 mmol/l)
Higher concentration
 Defect of excretion
(renal collapse)
 Extensive catabolism
of proteins (sepsis,
burn, polytrauma,
tumors, fever …)
Lower concentration
 Lack of proteins in food
 Defects of production
(liver collapse)
Biochemistry-7-1-AA 61
Character Urea Uric acid
Latine name Urea acidum uricum
Catabolit AA A,G
Behaviour n water Noelectrolyte Weak acid
pH Neutra Weak acidic
Solubility in water
Reduction protertyi
Good
No
bed
yes (antioxidante)
Body Liver Many tissues
In cells mitoch. + cytosol Cytosol
Concntration in plasma 2-8 mmol/l 150-400 μmol/l
Excretion of urine 20-35 g/d 0,5-1 g/d
% catabolic N 80-90 1-2
Biochemistry-7-1-AA 62
Regeneration of Aspartate
 PRODUCTION transamination from oxalcetate
(enzyme AST – aspartateminotransferase
 OA- intermediate of CAC
 Substrate for TA
 Substrate for 2-oxoglutarate (one reaction of CAC)
OA Asp
Biochemistry-7-1-AA 63
Synthesis glutamine
 Synthesis of Gln
 needs 1 ATP.
 In many cells, in mitochrondia
 Transport form of NH3, Gln is transported to kidney—NH3
Glutamine, Ala – overrepresented AA in blood n postresorpted phasis
Function, Role in organism:
a) Source of energy for some cells (enterocyty, fibriblasty, lymfocyty, makrofágy)
b) Source of N for synthesis (purines, aminosugers…)
c) Source of glutamate
2. Way for detoxication of
NH3
Biochemistry-7-1-AA 64
Synthesa glutamine
glutaminsynthetase
2. way detoxication NH3
glutamine
COOH
CH
CH2
H2N
CH2
C
O NH2
COOH
CH
CH2
H2N
CH2
C
O OH
+ NH3
glutamate
ATP ADP + P
- H2O
Biochemistry-7-1-AA 65
Gln Glu 2-oxoglutarate
NH3 NH3
H
+
H
+
NH4
+
NH4
+
urea
glutamatedehydrogenaseglutaminase
From glutamine in kidney release NH4
+
urea (pH ~ 5)
Biochemistry-7-1-AA 66
Glutamine and alanine has spetial importance
 The most representative AA in postresorption stage, muscular
tissue
 Ala – significant substrate for gluconeogenesis
 Synthesis Glutamine – detoxification of NH3
 Glutamine break-up NH3 in tubular cells of kidney
 Glutamine –exlusive source f energy for some cells (enterocyt,
fibroblast, lymfocyt, makrophag)
 Glutamine source of N for synthesis (purines, aminosugrs ...)
 Glutamine is source of glutamate (GSH, GABA, ornitine, prolin)
Biochemistry-7-1-AA 67
67
Glucoso-alanine cycle
Liver muscle
glucose
pyruvate
alanine
glucose
pyruvate
alanine
transamination
glycolysis
transaminatio
n
gluconeogenesis
transport by
blood
Biochemistry-7-1-AA 68
GMD r is reversibe reaction
Dehydrogenation deamination glutamate
Hydrogenation amination 2-oxoglutarate
COOH
CHH2N
CH2
CH2
COOH
NAD
+
NADH H
+
+
COOH
CHN
CH2
CH2
COOH
COOH
CO
CH2
CH2
COOH
H2O
NH3
Main NH3 formation in tissue
3. Way of detoxication of NH3
glutamát
2-iminoglutarate
Biochemistry-7-1-AA 69
Synthesis of non essential AA
Biochemistry-7-1-AA 70
Synthese of glycine
1. Reverse of transamination reaction
2. From
Serine
3. From Choline
CH2
NH2
COOH
CH
NH2
COOHCH2CH2HOOCC
O
COOHCH2CH2HOOC
C
O
COOH
H
+ +
2-oxoglutarate
glyoxalate
glutamate
CH2
OH
CH
NH2
COOH + FH4 CH2
NH2
COOH + HOCH2 FH4
serine glycine
Biochemistry-7-1-AA 71
Synthesis of Serine – from intermediate of glycolysis
glukosa
3-P-glycerate 3-P-hydroxypyruvate
3-P-serin
COOH
CH OH
CH2 O P
NAD
+
COOH
C
CH2 O P
O
NADH H
+
COOH
CH
CH2 O P
H2N
transamination
H2O
COOH
CH
CH2 OH
H2N
glucose
Biochemistry-7-1-AA 72
Synthesis of alanine from puruvate and
glutamate (ALT reversion reaction)
COOHCHH3C
NH2
COOHCH3C
O
Glu
2-oxoglutarate
ALT
alanine pyruvate
Biochemistry-7-1-AA 73
Synthesis of Aspartate from oxalacetate and
glutamate (AST reverse reaction)
AST production of Asp for synthesis of urea
COOHCHCH2
NH2
CH2HOOC
Asp
oxalacetate
AST
COOHCCH2
O
CH2HOOC
glutamate 2-oxoglutarate
Biochemistry-7-1-AA 74
Synthesis of proline is contrary of catabolism
N
COOH
H
H
H - 2H
proline
N
COOH
pyrrolin-5-carboxylate
aditioe H2O
N
C COOHO
H
H
H
glutamate-5-semialdehyde
H2N
HOOC COOH
glutamate
oxidation
Biochemistry-7-1-AA 75
COOH
CHH2N
CH2
CH2
COOH
NAD
+
NADH H
+
+
COOH
CHN
CH2
CH2
COOH
COOH
CO
CH2
CH2
COOH
H2O
NH3
Glutamate reduction amination of 2-oxoglutarate (GMD
opposite reaction)
L-glutamate 2-iminoglutarate 2-oxoglutarate
Biochemistry-7-1-AA 76
Hydroxylation of esential Phe – non esential Tyr
cofaktor tetrahydrobiopterine (BH4) is donor of 2 H
atoms, H2O formation
COOH
CHH2N
CH2
H
+ O O + BH4
COOH
CHH2N
CH2
OH
+ +H2O BH2
phenylalanine tyrosine
Biochemistry-7-1-AA 77
Glutamine formation from glutamate and NH3
Similar Asn (asparagine) from Asp
glutamine
COOH
CH
CH2
H2N
CH2
C
O NH2
COOH
CH
CH2
H2N
CH2
C
O OH
+ NH3
glutamate
ATP ADP + P
- H2O
Biochemistry-7-1-AA 78
Cysteine formation from degradation of
methionine
methionine
CH
NH2
COOHCH2
SH
HOOC CH
NH2
CH2CH2 SH
homocysteine
Condensation with serine
HOOC CH
NH2
CH2CH2 S
CH2 CH
NH2
COOH
H2O
cystathionine
Realise of cysteine
homoserine
HOOC CH
NH2
CH2CH2 OH
Biochemistry-7-1-AA 79
Selenocysteine formation by cotranslation of serine and
selenoposphate
Serine-tRNA + selenophosphate  selenocysteine-tRNA +
phosphate
SelenoP from selenid and ATP
Se2- + ATP + H2O  AMP + Pi + P
O
O
OSeH
COOHCH
NH2
CH2
Se
H
Glutathionperoxidaea (2 GSH + H2O2  2 H2O + G-S-S-G)
Dejodase of thyronine (thyroxin T4  trijodothyronin T3)
Thioredoxin reduktase (ribose  deoxyribose)
Biochemistry-7-1-AA 80
Biochemistry-7-1-AA 81
End Products Amino Acid
Ketogenic
Acetyl CoA
Acetoacetic Acid
Trp, Tyr, Thr, Ile, Leu,
Lys, Phe
Glucogenic
Pyruvate
Ala, Cys, Gly, Ser, Thr,
Trp
-ketoglutarate
Arg, Glu, Gln, His, Pro,
Succinyl-CoA Ile, Met, Val, Thr
Fumarate Asp, Phe, Tyr
Oxaloacetate Asp, Asn
Blue: Glucogenic and ketogenic
RED: ONLY Ketogenic