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skyblu280

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I'm having trouble plotting this data

Is there a way to attach the hw assignment so that you guys can view it?

Anyways, I'll type it for now:

We need to determine the dissociation constant for L (ligand) and the number of L binding sites on P using a scatchard plot.

here is the problem:

L is available in a radioactive form with an activity of 10^9 disintegrations per second per micromole of L. You set up a series of equilibrium dialysis experiments and add to each side:

There's a drawing of a dialysis membrane with the left side where you add one micromolar of protein and to the right you add various quantities of L.

It then says that after equilibration, you withdraw 10 microliters from the left and right side and determine how many disintegrations per second from each in 6 experiments with different amounts of radioactive L added: these are all in DPS=disintegrations per second)

LEFT SIDE RIGHT SIDE

25,000 10,000

44,000 20,000

60,000 30,000

100,000 60,000

135,000 90,000

200,000 150,000

Our professor gave us the equation that

So the y intercept is Sbound/Sfree while the x intercept is Sbound.

So I figured that the left side was the Sbound and the Sfree so in order to get the Sbound I had to subtract the right side which represents the Sfree. So the data is

bound free

15,000 10,000

24,000 20,000

30,000 30,000

40,000 60,000

45,000 90,000

50,000 150,000

And now he wants it in molar for x......so I was thinking that you take the S bound and change it to molar so you have 15,000* [10^9 disintegrations/(second *μmol)/ 10 microliters].....I did that and got

Sbound S bound/Sfree

1.5E+24 0.15

2.4E+24 0.12

3E+24 0.1

4E+24 0.066666667

4.5E+24 0.05

5E+24 0.033333333

and for my graph i got y=.2 ???? So i know there's something wrong. Also i know for the units like the micromole divided by 10 microliters i dont get molar right? I get 10^9 disintegrations/(second*umol*10*microliters)?