two sites ligand-receptor interaction
Ian A. Paul, Ph.D.
iap at anat.umsmed.edu
Fri Nov 10 10:04:48 EST 1995
Dear Dr. Bologna,
There are several iterative curve fitting programs which can
provide a two site model (saturation or displacement) and,
usually, can compare the goodness-of-fit between 1-, 2- or more
site models. These include GraphPad/Prism, Lundon, and
Ligand/EBDA. I believe Sigma-Plot also now handles
radioligand-type curve fitting but, I'm not familiar with the
algorithm that it employs.
As far as statistical analysis goes, most of these programs can
handle goodness-of-fit comparisons as mentioned. Some, such as
Prism, will perform comparisons between curves using a
two-factor ANOVA (i.e. treatment x ligand concentration).
However, this method makes the assumption that each factor
level is an independent variable. While this is usually valid
for treatment, ligand concentration is usually more accurately
viewed as a repeated measure. This is because the results
(dependent variables such as fmol/mg bound) at each
concentration are related inasmuch as the samples are drawn
from the same tissue pool. For that level of analysis, you
would need a serious statistical package (e.g. BMDP, SPSS,
Systat, SAS and the like).
Hope this helps.
Ian A. Paul, Ph.D.
Laboratory of Neurobehavioral Pharmacology and Immunology
Department of Psychiatry and Human Behavior
Division of Neurobiology and Behavior Research
University of Mississippi Medical Center
2500 North State Street
Jackson, MS 39216-4505
Tel.: (601) 984-5883/5898
Fax.: (601) 984-5884/5899
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