Talk:Fluorescence resonance energy transfer

Structure
Hi,

"...phosgene or rather triphosgene as a safe substitute serves as a linker between an acceptor and a donor coumarine." The coumarine, however, is labeled as the acceptor in the figure that follows it.

Structure
Hi, the structure for triphosgene in the FRET-phosgene detection scheme is wrong, it is a fluorine analog. Maybe this could be changed? I&#39;m with gerrit 18:47, 31 March 2007 (UTC)


 * Done! V8rik 19:41, 31 March 2007 (UTC)

Spectrum/Graph
Hi

I think that is would be more illustrative to have a spectrum that shows no FRET also. With the present spectrum I think it is difficult to see what distinguishes a FRET measurement from just taking an ordinary emission spectrum.

I think it would also be usefull to label the FRET graph.

I was thinking about creating a page for BRET (Bioluminescence Resonance Energy Transfer), but I am hesitating: It could just be a section in FRET. It's basically the same thing as FRET except that the photon emission from the donor is biochemically catalysed (by Luciferase-type donor]]) instead of being the result of exciting the donor with an external source. Result: You don't get background noise from the fluorescence of the donor in the results. I am too new to wikipedia to decide :) Looie 16:26, 16 November 2005 (UTC)

I resolved my moral dillema and simply added a small paragraph to the current page. Looie 04:11, 17 November 2005 (UTC)

Kappa squared comment is wrong.
Kappa squared only equals 2/3 when BOTH dyes are isotropically averaged. This should be obvious to anybody who considers the dipole electric field pattern in Three dimensional space. I have corrected the misstatement but I have not included a proper discussion of Kappa Squared. --128.6.78.114 21:09, 22 December 2005 (UTC)

Förster not Fluorescence
"Sometimes incorrectly referred to as Fluorescence Resonance Energy Transfer, FRET is the radiationless tranfer of energy from one molecule to another"

http://www.everything2.com/index.pl?node_id=625957 --JamMan 22:45, 25 May 2007 (UTC)
 * It turns out there is a parallel article Förster resonance energy transfer.
 * Fluorescence resonance energy transfer is linked from many articles, and Förster resonance energy transfer from only one, but if the "correct" name can be independently confirmed, then the two should be merged under that name and links updated as required. I'm happy to do the donkey work on this, if someone can authoritatively point out the correct answer. Clicketyclack 10:02, 5 June 2007 (UTC)
 * Gave it a week, but can't find an authoritative answer on this, so have redirected Förster RET here to avoid fork, and noted the second name in the intro. Clicketyclack 16:20, 12 June 2007 (UTC)


 * The Förster approach relies on non-radiative (electronic or more specifically dipole-dipole interaction) energy transfer so it is in fact not Fluorescence energy transfer this article is dealing with. Name suggestions: Resonance Energy Transfer (RET) or Excitation Energy Transfer (EET) or Electronic Energy Tranfer (EER). See the comments in section 4.6.3 in the Molecular Fluorescence book by Valeur.  Benkeboy (talk) 15:14, 22 November 2007 (UTC)

Citation for Overlap Integral?
I think the overlap integral is wrong. In particular, the standard formulation of FRET is in terms of the rate of energy transfer, which is
 * $$k_{\rm fret} = C \cdot {{\kappa^2} \over {R^6}} \int_0^\infty f_{\rm D}(\tilde{\nu}) \epsilon_{\rm A}(\tilde{\nu}) \tilde{\nu}^{-4} d \tilde{\nu}$$

(see, for example, VanBeek et al., Biophys J. 92:4168), where $$C$$ contains a variety of constants and $$\tilde{\nu}$$ is the wave number, i.e., $$\lambda^{-1}$$. But $$d \tilde{\nu} = -\lambda^{-2} d \lambda$$, so in wavelength form the integral ought to be
 * $$ J = \int_0^\infty f_{\rm D}(\lambda) \, \epsilon_{\rm A}(\lambda) \, \lambda^2 \, d\lambda $$

ought it not? Or does someone have a reference that shows otherwise?

(One obtains the equation for $$R_0$$ by setting the energy transfer rate equal to the rate of all other decays.)

--Ichoran 15:58, 12 June 2007 (UTC)

Answer: This is a common misconception. The integral is correct as shown in the article, as the fluorescence emission must also be transformed when making the change from wavenumber to wavelength. The situation is similar to that of the Planck distribution (blackbody radiation) whose maximum occurs at different energies (wavelengths, wavenumbers) depending on whether it is plotted on a wavelength scale or on a wavenumber scale. 193.136.128.7 13:42, 21 July 2007 (UTC)

Whoops, right, I'd overlooked that. Thanks! Ichoran 22:19, 27 July 2007 (UTC)

cartoon oddness
Is there any particular reason that the cartoon depicting FRET has titles that appear to be in Italian? "Nessun Segnale"? "Segnale"? --128.227.41.19 03:50, 29 June 2007 (UTC)

Clarity
Using this formalisation, what are the units for, the molar extinction coefficient, $$\epsilon_{\rm A}$$, the wavelength $$\lambda$$ and the Förster distance $$R_0$$.

Also how is the donor emission, $$f_{\rm D}$$ normalised? Is it such that the maximum value of the ordinate is unity or that the area under the curve is unity, $$ \int f_{\rm D}(\lambda) \, d\lambda = 1 $$

The reason for theses question is I have seen many different formalisation of FRET, what is considered the standard?