Chemistry Reference
In-Depth Information
H
Mg
+2
O
CH
2
O
-
O
-
O
-
H
O
-
Adenosine
O
P
O
P
O
P
H
H
O
O
O
H
OH
OH
OH
H
OH
ATP
Glucose
Nucleophilic attack of the C6
e
OH group of glucose on the
g
-phosphate of Mg
2
þ
e
ATP complex.
FIGURE 10.4
(Adapted from
Voet & Voet,
directly to the oxygen atoms of the
-phosphoryl groups, but also binds through a water molecule to the
carboxylate of a well-conserved Asp residue. This Asp acts as a general base responsible for deprotonating the
hydroxyl on the sugar which will be phosphorylated. This is illustrated for the rhamnulose kinase from E. coli
(
Figure 10.5
)
, which catalyses the transfer of the
b
- and
g
g
-phosphoryl group from ATP to the 1-hydroxyl group of
FIGURE 10.5
Stereoview of the reaction running through a bipyramidal pentavalent phosphorus atom. The
g
-phosphoryl group before and
after the transfer is in a transparent mode. A putative Mg
2
þ
was placed at the expected position between Asp10 and the
b
and
g
-phosphoryl
groups.
(From
Grueninger & Schultz, 2006
. Copyright 2006 with permission from Elsevier.)
L-fructose. The
-phosphoryl group of the ATP can be positioned in such a way that the three oxygen atoms are on
the corners of a trigonal bipyramid between O3
g
of ADP and the O1
00
atom of
b
b
-
L
-fructose. Moreover, the required
Mg
2
þ
can be modelled between the
-phosphoryl groups and the well-conserved Asp10, as shown in
Figure 10.5
.
The putative Mg
2
þ
binds directly to the phosphate oxygen atoms and through a water molecule to the
carboxylate group. Since Mg
2
þ
prefers an octahedral coordination sphere, it requires a water structure different
from that observed in holo rhamnulose kinase.
b
- and
g
