[Coastie17]

We were given a series of ligand concentrations and their corresponding absorbance values. We were then asked to guess the change in absorbance and then find the actual change in absorbance. We then had to find the %bound and %free as well as their corresponding concentrations. Finally, we were told to make the following graphs with the ultimate goal of identifying the dissociation constant:

1. bound/free vs. bound
2. change in absorbance vs. ligand concentration
3. 1/change in absorbance vs. 1/ligand concentration

My graphs do not appear to make sense and I am not sure where I went wrong. I have attached a link to the spreadsheet I made of my work. Thank you for any help.

https://docs.google.com/file/d/0BwfrEPxlvXJqVk1zdFhqLW5pS2M/edit?usp=sharing

[Babcock_Hall]

It might help if you described the system and the experiment in greater detail.  Also, were you given some equations, or were you expected to derive them?

[aHerraez]

There are details hard to understand there:

1. change in absorbance, as a consequence of what?

2. a Scatchard plot is a graph for ligand binding data, and indeed you mention bound and free and a dissociation constant. Where and which is the receptor for that ligand?
 
If you have interpreted something wrong, such as change in absorbance, it may well be the reason for the funny graphs