Lineweaver-Burk Plot of MI-1-Pase Activity With and Without Lithium

Most people with bipolar disorder take medication to regulate their moods.
Lithium (an alkali metal) has been widely used as a mood stabilizer and is
generally the first line of treatment for manic episodes.
Lithium appears to act by suppressing the formation of second messengers
involved in neurotransmitter signal transduction. Lithium reduces the formation
of a second messenger molecule called IP 3 by inhibiting the enzyme myo-inositol-
1-phosphatase (MI-1-Pase). By reducing IP 3 formation, Lithium reduces the
neuronal response to serotonin and norepinephrine, whose effects are partly
mediated by IP 3 .
Below, you will find enzyme kinetics data on the enzyme myo-inositol-1-
phosphatase (MI-1-Pase) in both the absence of Lithium and in the presence of
Lithium. Given this data, calculate or construct the following:
[S]
(mM)
Velocity in absence of
Lithium
(μM /s)
Velocity in presence of
Lithium
(μM /s)
1 0.9 0.65
2 1.5 0.9
5 2.6 1.3
10 3.5 1.4
20 4.1 1.5
a) Construct a Lineweaver-Burk plot using the data given above using Microsoft
Excel or similar program/app/tool