Texas Red


 * ''For the professional wrestler, see Mark Calaway
 * ''For the food, see chili con carne.

Texas Red (TR) is a red fluorescent dye, with a molecular weight of 625 daltons, used in histology for staining cell specimens. Texas Red is a sulfonyl chloride derivate of sulforhodamine 101. It is used for fluorescent-activated cell sorting machines, in fluorescence microscopy applications, and in immunohistochemistry. It can be excited by a dye laser tuned to 595-605 nm, or less efficiently a krypton laser at 567 nm.

Texas Red fluoresces at about 615 nm, and the peak of its absorption spectrum is at 589 nm. It is relatively bright, and therefore can show even weakly expressed antigens.

Texas Red can be used as a marker of proteins, with which it easily form conjugates. A protein with the chromophore attached can then act as a fluorescent labelling agent; an antibody with a fluorescent marker attached will bind to a specific antigen and then show the location of the antigens as shining spots when irradiated. Other molecules can be labeled by Texas Red as well, eg. various toxins.

Texas Red, attached to a strand of DNA or RNA, can be used as a molecular beacon for highlighting specific sequences of DNA. Texas Red can be linked with another fluorophore. A tandem conjugate of Texas Red with R-phycoerythrin (PE-Texas Red) is often used.

Fluorophores, like Texas Red, are commonly used in molecular biology techniques like quantitative RT-PCR and cellular assays.

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