Chemistry Reference
In-Depth Information
hydrophobicity of the grafted MMA regions, as well as the Coulomb forces and
hydrogen bonding forces, thus giving rise to a reversible equilibrium relationship.
The Michaelis-Menten complex formation reaction is thought to occur as follows:
Formed complex amount
¼ K
1
ð
DNA concentration
Þð
DDMC concentration
Þ
(6.37)
The amount of formed complex is proportional to the RLU value. The formation
reaction for the complex between DEAE-dextran and DNA is nearly non-reversible
because it depends mostly on Coulomb forces, and the reaction is first-order with
respect to DEAE-dextran concentration. The reaction is thought to be expressed as
follows:
Complex formation amount
¼ K
2
ð
DEAE-dextran concentration
Þ
(6.38)
The complex formation capacity is thought to give rise to a reversible equilib-
rium relationship, which can be expressed as a Michaelis-Menten equation:
K
m
½Eþ½S
!
½ES
½
E
½
S
=½
ES
¼K
m
(6.39)
Normally, the relationship is between enzyme and substrate, but in this case [E]
is used to represent the concentration of DEAE-dextran or DDMC, and [S] is used
to represent DNA concentration. Taking the initial DEAE-dextran or DDMC
concentration as [E]
0
, then:
½
E
¼½
E
0
½
ES
(6.40)
Inserting these values, the complex concentration becomes:
½
ES
¼½
E
0
½
S
=ðK
m
þ½
S
Þ
(6.41)
With DDMC, the Coulomb forces are small (low affinity between E and S, and
the fact that [S] is small has a direct influence on the complex formation). As
K
m
increases, the complex becomes unstable, and [S] is negligible relative to
K
m
. With
this formula, assuming
K
m
[S], the complex concentration becomes:
½
ES
¼½
E
0
½
S
=K
m
(6.42)
This is the case for DDMC, and it is highly likely that the complex is strongly
influenced by concentration conditions. In other words, it is thought that a very low
DDMC concentration will have a significant influence on complex formation.
