Biomedical Engineering Reference
In-Depth Information
K
1
+
ADP
+
H
+
+
Hx
(1)
ATP
+
Hexokinase (Hx)
+
Glucose (G)
Glucose-6-Phosphate (G6P)
K
2
(2)
Phosphoglucose Isomerase (PI)
+
Glucose-6-Phosphate
Fructose-6-Phosphate (F6P)
+
PI
K
-2
K
3
Fructose-1,6-Bisphosphate
(F6BP)
+
ADP
+
H
+
+
PF
ATP
+
Phosphofructokinase (PF)
+
(3)
Fructose-6-Phosphate
K
4
Dihydroxyacetone-Phosphate
(DP)
Glyceraldehyde-3-Phosphate
(G3P)
(4)
Aldolase (ALD)
+
Fructose-1,6-Bisphosphate
+
ALD
+
K
-4
K
5
(5)
Triose Phosphate Isomerases (TPI)
+
Dihydroxyacetone-Phosphate
Glyceraldehyde-3-Phosphate
+
TPI
K
-5
K
6
2(Glyceraldehyde 3-Phosphate
Dehydrogenase) (GPD)
+
2P
+
2NAD
+
+
2(1,3-Bisphosphoglycerate)
(BP)
+
2(NADH
+
H
+
)
+
2GPD
(6)
2(Glyceraldehyde-3-Phosphate)
K
-6
K
7
2(Phosphoglycerate Kinase) (PGK)
+
2ADP
+
(7)
2(1,3-Bisphosphoglycerate)
2(3-Phosphoglycerate) (P3G)
+
2ATP
+
2PGK
K
8
2(Phosphoglycerate Mutase)
(PM)
+
2(3-Phosphoglycerate)
2(2-Phosphoglycerate) (P2G)
(8)
+
2PM
K
-8
K
9
2Enolase (EN)
+
2(2-Phosphoglycerate)
2(Phosphoenolpyruvate) (PP)
+
2EN
+
H
2
O
(9)
K
-9
K
10
(10)
2Pyruvate Kinase (PK)
+
2ADP
+
2(Phosphoenolpyruvate)
2(Pyruvate) (PV)
+
2ATP
+
2PK
FIGURE 8.24
An overview of the 10 steps of glycolysis. Note that in steps 6-10, there are two molecules of
everything, since 2 molecules of glyceraldehyde-3-phosphate are created for each glucose molecule. Also note that
the intermediate complex reactions are not included in the illustration but are included in the differential equations
describing glycolysis. Abreviations are listed next to each molecule.
Step 1 of glycolysis begins with the binding of glucose to a phosphate enzyme called
hexokinase, resulting in glucose-6-phosphate. The immediate phosphorylation of glucose
is required so glucose does not leave the cell. This reaction requires ATP and is given by
B
1
G
þ
Hx
!
GHx
GHx
þ
ATP
!
K
1
P
þ
ADP
þ
H
þ
þ
Hx
G
6
ð
8
:
89
Þ
q
G
¼
B
q
G
q
Hx
þ
J
G
1
q
GHx
¼
B
q
G
q
Hx
K
q
ATP
q
GHx
1
1
where
J
G
is the flow of glucose into the cell, as described in Section 8.4.3.
The second step involves the reaction of glucose-6-phosphate with the enzyme phospho-
glucose isomerase enzyme to create fructose-6-phosphate. This reaction is given by
ð
8
:
90
Þ
