Biology Reference
In-Depth Information
FIGURE 8.2
The enzyme glucokinase, from
http://commons.wikimedia.org/wiki/File:Glucokinase-
Generally, in each biochemical reaction step in a metabolic system, the reaction is
enzymatic
, in that enzymes, special proteins, catalyze these biochemical reactions.
The hexokinases are enzymes that carry out this step from glucose to G-6-phosphate.
Figure 8.2 [3] shows a particular hexokinase, glucokinase. Beyond its importance in
glycolysis, functional mutations in glucokinase are responsible for Type II diabetes,
so there is special interest in targeting this enzyme. (As for many proteins, incorrect
folding can lead to disease.)
By many common ways of describing glycolysis, there are 9 further reactions in
the glycolysis pathway, with the total of 10 reactions involving a total of 17 (differ-
ent) compounds as metabolites (some as substrates, some as products, and most as
both). For a movie that illustrates this process step-by-step, along with the reaction
chain of gluconeogenesis that produces glucose, rather than breaking it down, do
9594/2456197.cw/-/2456228/index.htm
.
For a static picture, see Figure
8.3
[
4
]; the reader is encouraged to look on the Web or in texts like [1] for others to
see a multiplicity of perspectives.
Coming back to the reactions themselves, if we were to label the compounds with
the generic variables above, we would need 10 chemical equations in 17
variables,
C
1
,...,
C
17
. Two additional examples of these chemical reactions involved
in glycolysis are:
(
1
,
3BPG
)
+
ADP
−→
(
3PG
)
+
ATP
,
(8.3)
and
H
+
−→
(
(
PEP
)
+
ADP
+
Pyr
)
+
ATP
,
(8.4)
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