The isomeric mixture of Texas Red-X reactive with amine, succinimidyl ester, and their conjugates emit at a longer wavelength than tetramethylrhodamine or lissamine rhodamine B and are among the most widely used long-wavelength “third brands” in fluorescence and flow microscopy. cytometry. Protein conjugates prepared with Texas Red-X succinimidyl ester also have a higher fluorescence yield than those with the same ratio of labeling prepared with Texas Red sulfonyl chloride.
Chemical reaction: Amine
Shipping condition: Room temperature
Label Type: Classic Dyes
Label or tint: Texas Red ™
Product line: Texas Red ™
Reactive rest: Active ester, succinimidyl ester
Content and storage
Store in a freezer (-5 to -30 ° C) and protect from light.
Texas Red Sulfonyl Chloride (TR-SC) and Lysamine Rhodamine B Sulfonyl Chloride (LRB-SC) are popular dyes that are often used to prepare red fluorescent conjugates that are useful second labels in combination with fluorescein. Unfortunately, being derivatives of sulfonyl chloride, both are unstable to moisture during storage and prone to hydrolysis in the conjugation reaction. Its instability causes the percentage of reactive dye to vary from batch to batch and requires the use of low temperatures and a relatively high pH to optimize conjugation efficiency.
Succinimidyl esters of the aminohexanoic acid sulfonamides of both dyes have been prepared, which are named Texas Red-X succinimidyl ester (TR-X-SE) and Rhodamine Red-X succinimidyl ester, respectively. Its spectral properties are similar to those of its sulfonyl chloride analogs; furthermore, the incorporation of the succinimidyl ester at the end of the aliphatic chain spacer facilitates conjugation, decreases protein precipitation during conjugation and storage, and typically increases the fluorescence yield of the conjugate.
Comparison of the hydrolysis rate of TR-SC with that of TR-X-SE shows that, while the former was completely hydrolyzed in 5 minutes by exposure to water, TR-X-SE retains most of its reactivity during more than one hour. . The reactivity of both new derivatives is high between pH 7.5 and 8.5, which allows the conjugation of proteins that do not tolerate the high pH required for the reaction with sulfonyl chlorides. In addition, Texas red maleimides and haloacetamides were prepared to contain spacer groups to label sulfhydryl groups.