Tetramethylrhodamine-5 -iodoacetamide

The spectral properties of these derivatives are similar to native rhodamine. The excitation maximum occurs at about 543 nm and its emission peak at 567nm, producing light in the orange-red region of the spectrum. The extinction coefficient of tetramethylrhodamine-5-(and-6)-iodoacetamide in methanol at its wavelength of maximum absorptivity, 542 nm, is 81,000M-1cm-1. 

Figure 9.18 This iodoacetamide derivative of tetramethylrhodamine can be used to label sulfhydryl groups via thioether bond formation.

Prepare a 20mM tetramethylrhodamine-5-(and-6)-iodoacetamide solution by dissolving 11.3 mg/ml of DMF. Prepare fresh and protect from light. 

The following protocol for labeling proteins with tetramethylrhodamine-5- (and 6)-iodoacetamide represents a general guideline. The procedure should be optimized for each macromolecule being labeled to obtain the best F/P ratio to produce intense fluorescence and high activity in the final complex. 

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