1,5-I-AEDANS

V-iodoacetyl-V -(5-sulfo- l-naphthyl)ethylenediamine (IAEDANS or 1,5-I-AEDANS) is used for fluorescent labeling of electroblotted proteins on blot transfer membranes. Because IAEDANS reacts with free cysteines, disulfides in the sample must first be reduced with dithiothreitol (DTT). Transferred protein bands are visualized under UV light. 

Abbreviations dansyl> 5-dimethylamino-l-naphthalenesulfonic acid FITC, fluorescein,5-isothiocyanate 1.5-I-AEDANS 5-((((2-iodoacetyl)amino)ethyl)amino)naphthalene-l-sulfonic acid ODR, octadecyl-rhodamine. 

As an illustration of the FRET technique, consider a study of the protein rho-dopsin (Case study 12.2). When an amino acid on the surface of rhodopsin was labeled covalently with the energy donor 1.5-I-AEDANS (2), the fluorescence quantum yield of the label decreased from 0.75 to 0.68 due to quenching by the visual pigment 11-cis-retinal (Atlas E3 and 3). From eqn 12.26, we calculate tJt = 1 - (0.68/0.75) = 0.093, and from eqn 12.27 and the known value of Rg = 5.4 nm for the 1.5-I-AEDANS/11-cis-retinal pair we calculate R = 7.9 nm. Therefore, we take 7.9 nm to be the distance between the surface of the protein and 11-ds-retinal. 

I-AEDANS iV-lodoacetyl-Ai -(X-sulfo-l-naphthyl)ethylenediamine (X = 5, 1,5-1-AEDANS X = 1,8-1-AEDANS)... 

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