NH
4
+
NH
4
+
Alanine
Glucose
Glucose
2-Oxoglutarate
2-Oxoglutarate
2-Oxoglutarate
Glutamate
Glutamate
Glutamate
Glutamine
H O
2
Carbamoyl-P
HCO
3
-
2ATP
ATP
2ADP
P
i
P
i
2-Oxoglutarate
Ornithine
Ornithine
Ornithine
Citrulline
Citrulline
Aspartate
Aspartate
AMP
PP
Argininosuccinate
Alanine
i
Fumarate
Oxaloacetate
Arginine
-OOCCH=CHCOO-
-OOCCH(OH)CH
2
COO-
-OOCCOCH
2
COO-
-
-
-
OOCCH CHCOO
2
(NH
)
3
+
DEAMINATION OF AMINO ACIDS - THE UREA CYCLE
Glutamate
Glutamate
Glutamine
OXIDATIVE
DEAMINATION
Gluconeogenesis
Catabolism etc.
Catabolism and/or
RCH
(NH
3
)
COO
-
+
RCH
(NH
3
)
COO
-
+
-
OOCCH
2
CH
2
CH
(NH
3
+)
COO
-
CH
3
CH
(NH
3
+)
COO
-
CH
3
CH
(NH
3
+)
COO
-
-
OOCCH
2
CH
2
CH
(NH
3
+)
COO
-
-
OOCCH2CH2CH
(NH
3
+)
COO
-
-
OOCCH2CH2CH
(NH
3
+)
COO
-
H
2
NOCCH
2
CH
2
CH
(NH
3
+)
COO
-
-
OOCCH2CH2COCOO
-
R.COCOO -
H3N[CH2]3CH(NH3+)COO-
H3N[CH2]3CH(NH3+)COO-
HN[CH2]3CH(NH
3
+
)COO-
Pyruvate
Pyruvate
-OOCCH CHCOO-
2
AMINO ACID I
AMINO ACID II
AMINO ACID I
AMINO ACID II
2-Oxo acid
2-Oxo acid
H2N
-
CO
-OP
H
2
N
-
C-
HN[CH2]3CH(NH
3
+
)COO-
HN[CH2]3CH(NH
3
+
)COO-
H
2
N=
C-
NH
H
2
N=
C-
NH
2
O
=
+
+
H
2
N-
CO-
NH
2
UREA
1.5 NADPH
NAD(P)H
1.5 NADP
+
NAD(P)
+
1.5O
2
NO
.
UREA CYCLE
REACTANTS PRODUCTS
MUSCLE
LIVER
UREA CYCLE
MITOCHONDRIAL INNER MEMBRANE
MITOCHONDRIAL INNER MEMBRANE
MITOCHONDRIAL MATRIX
NH
4
+
ADP+Pi
1.14.13.39
1.4.1.3
2.1.3.3
2.6.1.
2.6.1.
2.6.1.1.
2.6.1.2
2.6.1.2
3.5.1.2
3.5.3.10
4.3.2.1
6.3.1.2
6.3. 4.5
6.3.4.16
+ ATP
N-Acetylglutamate
GLYCOLYSIS
Urea
Glutamine
Glutamate
NH
4
+
NH
4
+
UREA CYCLE EQUATION
Aspartate
UREA
Fumarate
NH
4
+
+
HCO
3
-
+
-
OOC.CH
2
CH
(NH
3
+
)
COO
-
+ 3ATP
H
2
N
.
CO
.
NH
2
+
-
OOCCH=CHCOO
-
+ 2ADP + 2P
i
+ AMP +PP
i
AMINO ACIDS
GLUTAMATE
GLUTAMATE
GLUCOSE
ALANINE
CYCLE
LEUCINE, ISOLEUCINE, VALINE
MAINLY
AMINO ACIDS
3.5.3.10
Arginase
1.14.13.39 Nitric-oxide synthase
1.4.1.3
Glutamate dehydrogenase (NAD(P)
2.1.3.3
Ornithine carbamoyltransferase
2.6.1.-
Amino acid aminotransferase
2.6.1.1
Aspartate aminotransferase
ENZYMES
(ammonia)
6.3.4.16 Carbamoyl-phosphate synthase
1.1.1.37
Malate dehydrogenase
4.2.1.2
Fumarate hydratase
4.3.2.1
Argininosuccinate lyase
6.3.1.2
Glutamate-ammonia ligase
(Glutamine synthase)
6.3.4.5
Argininosuccinate synthase
3.5.1.2
Glutaminase
2.6.1.2
Alanine aminotransferase
Malate
Oxaloacetate
NAD
+
NADH+H
+
Gluconeogenesis
c 2001 IUBM B
U
R
E
A
C
Y
C
L
E
G
lu
con
eogen
es
is
H
2
O
2-Oxoglutarate
Glucose
SKELETAL & HEART MUSCLE, KIDNEY
Transport to Liver
3.5.1.2
1.4.1.3
CELL MEMBRANE
CELL MEMBRANE
CYTOSOL