Hi, this is Dr. Vijay. Today I am going to explain Lineweaver-Burk

or double reciprocal plot, from this we can easily calculate Km and Vmax. Before going to Lineweaver-Burk plot, we can

see here, which we studied in the previous video, we got here hyperbolic curve and the

equation is, the Michaelis-Menten equation is, from this hyperbolic curve, the initial

velocity is equal to maximum velocity multiplied by concentration of the substrate divided

by Km value plus concentration of the substrate. So, this equation, Michaelis-Menten equation

derived from this hyperbolic curve. You can see here from this plot, in order

to calculate Km value, we should know the maximum velocity. From the maximum velocity or Vmax, we are

going to take half the maximum velocity and then we can calculate Km value. So, from this graph practically not always

possible to achieve the maximum velocity. If you want to achieve maximum velocity, we

should have a large amount of substrates. So, it’s may be sometimes it’s not practical

to calculate Km from the maximum velocity because to achieve maximum velocity, we should

have a lot of substrates and curve itself is a hyperbolic curve Suppose we make this

equation, Michaelis-Menten equation to a linear form of graph or the linear form of equation,

then it is easy to extend that line in order to calculate either Km or Vmax. That is a Lineweaver-Burk plot or double reciprocal

plot. So, this Lineweaver-Burk plot is done by taking

this Michaelis-Menten equation. So, it is nothing but they are taking reciprocal

of this Michaelis-Menten equation. So, by taking reciprocal of this equation

we can plot what is called Lineweaver-Burk plot or double reciprocal plot. First, I’m going to explain how to derive

the equation, that is Lineweaver-Burk equation, it is nothing but reciprocal of Michaelis-Menten

equation. So, let me write first Michaelis-Menten equation,

the initial velocity or velocity is equal to maximum velocity Vmax, multiplied by the

concentration of substrate, divided by Km plus the concentration of substrate. This is Michaelis Menten equation. So, we will do reciprocal of this equation. That is one by velocity or initial velocity

is equal to, we are going to taking reciprocal of this equation, so this Km plus substrate

will come to the numerator, Vmax multiplied by concentration of substrate. If you simplify the equation, Km divided by

Vmax, times substrate concentration plus the concentration of substrate divided by Vmax,

multiplied by concentration of substrate. So, we can cancel this concentration of substrate

here. So, one by velocity is equal to Km by Vmax,

so this substrate concentration we can write one by concentration of the substrate plus

one by Vmax. So, by looking at this equation, suppose we

plot the velocity and the one by substrate concentration, we will get a linear equation. So, I’m going to show this graph, that is

double reciprocal plot. So, this equation is derived from by taking

the reciprocal of Michaelis Menten Equation. From this equation, we can easily calculate

Vmax, the reaction need not achieve the maximum velocity. If you plot one by substrate concentration

and one by velocity. Now here I am going to take, so in the X-axis

on right hand side, I’m going to take one by substrate concentration and in the Y-axis,

I’m going to take the velocity. Now I will plot a graph, suppose if you go

on increasing the one by substrate concentration and velocity also increases, so the graph

looks like this, we got a linear from of graph if you increase one by substrate concentration

the velocity also increases we got a graph here. Now if you extend this graph, so we need not

wait for the maximum velocity because this graph is a linear from. Now we will extend this graph, it will bisect

Y-axis and further if you extend is graph it will bisect the X-axis also and we got

now 2 intersection points. So, now after extending this line, this line

intercept Y-axis at a point and also it intercepts X-axis at a point. The line of intersection at the X-axis is

nothing but minus one by Km and the line which intercepts Y-axis that point is going to be

our one by Vmax. So, what we have done? we plotted the one

by substrate concentration on X-axis versus one by initial velocity on Y-axis. So, we got a graph that is linear form till

here, from here to here and we extend this line backwards, so that this line intercepts

Y-axis that intersection point is now our one be maximum velocity and still if you extend,

go on extend, it will intercept X-axis and that point going to be our minus one by Km

value. So, by using this Lineweaver-Burk plot, we

can calculate Km and Vmax very easily, that is 2 intercept points and another important

significance of this Lineweaver-Burk plot is we can study mechanism of action of enzyme

inhibitors. So, I’m going to explain in the future videos,

the enzyme inhibition by using this Lineweaver-Burk plot, that is why I made this video. So, you need to understand the Lineweaver-Burk

plot or double reciprocal plot is a just simply a reciprocal of Michaelis Menten equation,

where it is a hyperbolic plot, here in this it is a linear equation. So, by using this linear equation, we can

easily calculate Km and Vmax. We need not wait for the maximum velocity

to achieve because in order to achieve maximum velocity we require a lot of substrate concentration

and by using the equation we can easily calculate Km and Vmax and also, we can study the action

of enzyme inhibitors. So, this is about Lineweaver-Burk plot or

double reciprocal plot. Thanks for watching.