It is common to want to take data from one computer program and analyze it with another. One has to deal with file export / import issues to achieve this objective.

Here is an example. Say we collected some CD data in a GuHCl titration experiment and want to make a plot representing the denaturation and refolding of a protein. We collect CD data for all concentrations of GuHCl over the wavelengths 270nm to 220 nm (denature.exe is a self-extracting zip file with the data files; save it to your directory, and double click on it from the WindowsNT Explorer, or Start_Run_browse and find the file, and run it; note that 0824scan files are the denaturation experiment, and 0825scan files are the refolding experiment; in case this does not work, I've placed the files on the class ftp site also under the Excel_Denature folder). The way the CD spectrometer and software work, each scan is in a separate ascii text file, with each one's name reflecting its postition in the titration series (###.001 is the first scan, ###.002 is the second, and so on). Another program wrote an ascii text file with the titration series in it (denature schedule, refold schedule). Use these two text files to obtain the [GuHCl] for each titration.

Your assignment is to use MS Excel to import these ascii text files, and to:

• plot a graph of the serial scans with CD vs wavelength over the entire series
• plot a graph of 220 nm signal vs [GuHCl]
• The experiment was also performed in reverse, starting with denatured protein and slowing removing the GuHCl. Add the re-folding curve to the plot  you just made (CD220nm vs [GuHCl].
• Play with Excel to label the plot and its legend, rescaling if needed, etc.
• Now, make bitmap images of your plots and post an html page describing your effort on this exercise.

Hints

• Import can import more than one file at a time.
• Features can be typed in with the keyboard.
• Cutting and pasting can be dull and give you a sore hand, but it often has to be done.
• One could write a simple program to do most of the data editing.
• Want to try it?

To create a graph

• make columns of [GuHCl] or wavelengths and observations,
• click on the graph icon,  
• pick scatter plot;
• pick by series,
  • click on the right side of X,
    • select X cells,
    • click on right side of X-axis window;
  • repeat for Y;
• repeat for each plot desired;
• or select a series of columns to plot by area.

To make a bitmap of the graph after you have all of its settings as you want them,

• select the graph,
• hold down the shift key and use the mouse to select edit_copy
• and follow the instructions.
• An alternative is to export the data as an ascii text file and import it into a plotting program.