Page 196 - The Manga Guide to Biochemistry

Let’s calculate Vmax and Km! I hope I don’t
screw this up...
Now, let’s try to figure
out the Vmax and Km values

of a particular enzyme!

We’ll use DNA Let’s assume this experiment produced
polymerase, which the following measurements:

is an enzyme for Substrate produced Reaction
synthesizing DNA, as concentration product
→
an example. 0 µM → 0 pmol
1 µM → 9 pmol
Nucleotides, the building blocks of DNA, 2 µM → 15 pmol
will be the substrate in this example. 4 µM → 22 pmol
10 µM → 35 pmol
Let's say we add DNA polymerase 20 µM 43 pmol
to six different solutions
These results show the
with the following substrate concentration of reaction
concentrations:* product formed over the
course of an hour, so we can
Substrate concentration divide these values by 1 hour to
turn them into reaction rates.**
0 µM
1 µM
2 µM
4 µM
10 µM
20 µM

Then we let the reaction
run for 60 minutes at a

temperature of 37°C.

Now, let's graph When the substrate Oookay!
these results!
concentration is 0 µM,
the measured result is

0 pmol, so...

Reaction rate
(pMol/hour)

substrate
concentration (µM)

We'll let the x-axis
(horizontal axis) be the
substrate concentration
(µM) and the y-axis be the

reaction rate (pMol).

* Actually, we’d also need to add template DNA, magnesium ions, and other elements, but
let's keep things simple!

** For example, if we start with a substrate concentration of 1 µM, our reaction rate is
9 pmol per 1 hour, or, simply, 9 pmol/hour.