Hi Tami,
 
Try nof to fit the curve into excel because you need the curve fitting formula and excel cannot give this correctly. Pleasy try and use kaleidagraph or slidewrite. Furthermore it is important wheterh you use a bleached spot or a bleached stripe in the experiment. If you use a bleached stripe the diffusion constant comes immediately from the curve fitting
 
I(t) = I(final) (1- (W^2(w^2+4*pi*D*t)^-1)^0.5)
 
where W = the width of the stripe bleahced (ellenberg et al, Dynamics and mobility of nuclear envelope proteins in interphase and mitotic cells revealed by GFP chimeras)
 
When you bleach a spot the curve fits to
 
I(t) = I(0) + (F(final)-F(0))(1-e^-k*t)
 
T(1/2) = ln(2)/k
 D= w^2/(4*t(1/2))
 
where w = the radius of the bleached spot (Hush et al, Quantification of microtubule dynamics in living plant cells using FRAP, journal of cell science 107, 775-784 (1994)
 
Hope this helps
 
Joost Willemse
Wageningen University and research centre
Dept. Molecular Biology
Dreienlaan 3
6703 HA Wageningen
Netherlands
+31(0)317-484574
 
 
-----Oorspronkelijk bericht----- 
Van: Confocal Microscopy List namens Tamara Casavan 
Verzonden: do 17-6-2004 22:09 
Aan: [log in to unmask] 
CC: 
Onderwerp: FRAP



	Search the CONFOCAL archive at
	http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal
	
	Does anyone know a straight-forward way for calculating a diffusion
	coefficient from a fluorescence recovery curve?  We have fitted a trendline to
	the curve in Excel - but I am not sure where to go from there.
	
	Thanks for any suggestions/resources.
	
	Tami Casavan
	Anatomy & Cell Biology Dept.
	UND Medical School