Tetramethylrhodamine with Lissamine rhodamine

The spectral characteristics of protein conjugates made with Lissamine rhodamine B derivatives are of longer wavelength than those of tetramethylrhodamine—more toward the red region of the spectrum. In addition, modified proteins have better chemical stability and are somewhat easier to purify than those made from TRITC (discussed previously). Lissamine derivatives also make more photostable probes than the fluorescein derivatives (Section 1, this chapter). 

Texas Red hydrazide is a derivative of Texas Red sulfonyl chloride made by reaction with hydrazine (Invitrogen). The result is a sulfonyl hydrazine group on the No. 5 carbon position of the lower-ring structure of sulforhodamine 101. The intense Texas Red fluorophore has a QY that is inherently higher than either the tetramethylrhodamine or Lissamine rhodamine B derivatives of the basic rhodamine molecule. Texas Red s luminescence is shifted maximally into the red region of the spectrum, and its emission peak only minimally overlaps with that of fluorescein. This makes derivatives of this fluorescent probe among the best choices of labels for use in double-staining techniques. 

This approach has been shown to work with a number of different fluorescent probes such as the short-wavelength fluorophores dansyl sul-fonyl chloride and coumarin chloride and the long-wavelength fluorophores tetramethylrhodamine-5-(and-6)-isothiocyanate [5(6)-TRITC], 5-(and-6)-carboxytetramethylrhodamine, succinimidyl ester [5(6)-TAMRA, succin-imidyl ester] and lissamine rhodamine B sulfonyl chloride (each in conjunction with different binding functionalities on the SAM surface. 

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