Biomedical Engineering Reference
In-Depth Information
H
2
O
+
Citrate Synthase (CS)
+
(1)
K
1
+
CoA-SH
+
AC
Acetyl CoA (AC)
Oxaloacetate (O)
Citrate (CT)
+
K
2
K
-2
K
3
(2)
Aconitase (AT)
+
Citrate
Isocitrate (IT)
+
AT
NAD
+
+
Isocitrate
Dehydrogenase (ID)
+
(3)
+
(NADH
+
H
+
)
+
CO
2
+
ID
Isocitrate
a
-Ketoglutarate (KG)
K
-3
K
4
+
(NADH
+
H
+
)
+
CO
2
+
KGH
a
-Ketoglutarate Dehydrogenase
(KGH)
+
NAD
+
+
CoA-SH
+
a
-Ketoglutarate
Succinyl-CoA (SC)
(4)
K
5
Succinyl-CoA Synthetase (SCS)
+
ADP
+
P
+
+
CoA-SH
+
ATP
(5)
Succinyl-CoA
Succinate (ST)
K
-5
K
6
Succinate Dehydrogenase (STD)
+
FAD
+
Succinate
Fumarate (FT)
+
FADH
2
+
STD
(6)
K
-6
K
7
Fumarase (FS)
+
H
2
O
+
Fumarate
Malate (MT)
+
FS
(7)
K
-7
K
8
Malate Dehydrogenase
(MTD)
+
NAD
+
+
+
MTD
+
(NADH
+
H
+
)
(8)
Malate
Oxaloacetate
K
-8
FIGURE 8.25
Overview of the Krebs cycle.
NAD
þ
with the enzyme isocitrate
The third step involves the reaction of isocitrate and
NADH
þ
H
þ
dehydrogenase to create a
ketoglutarate,
ð
Þ
and
CO
2
, which is given by
ð
8
:
106
Þ
NAD
þ
and
The fourth step involves the reaction of a
ketoglutarate
,
CoA
with the enzyme
NADH
þ
H
þ
a
ketoglutarate dehydrogenase to create succinyl
CoA,
ð
Þ
,and
CO
2
:
This
reaction is given by
B
4
KG
þ
KGH
!
KGKGH
KGKGH
þ
NAD
þ
þ
CoA
SH
!
K
4
SC
þ
KGH
þ
NADH
þ
H
þ
ð
Þ þ
CO
2
ð
8
:
107
Þ
q
KG
¼
K
q
ITID
q
NAD
þ
B
q
KG
q
KGH
K
3
q
KG
q
ID
q
NADH
þ
H
þ
q
CO
2
3
4
q
KGKGH
¼
B
q
KG
q
KGH
K
q
KGKGH
q
NAD
þ
q
CoA
4
4
