Description
Texas Red NHS Ester (TR-4-SE) – Bright Red Fluorescent Dye for Amine Labeling
Texas Red NHS Ester (TR-4-SE) is a single-isomer, amine-reactive rhodamine dye ideal for covalent labeling of proteins, peptides, and alkylamino-modified nucleic acids. With strong absorption at 579 nm and a sharp emission peak at 591 nm, it is a preferred choice for red-channel fluorescence applications. The dye exhibits excellent brightness, high molar absorptivity, and compatibility with a variety of biological buffers and solvents.
Performance Highlights
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Single-isomer NHS ester for consistent labeling
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Excitation/emission maxima: 579 nm / 591 nm
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High molar absorptivity: ε > 106,000 M⁻¹·cm⁻¹
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Bright red fluorescence with excellent signal-to-noise
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Compatible with standard amine-labeling protocols
Properties
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Molecular Weight: 704
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Empirical Formula: C₄₁H₄₄N₄O₁
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CAS Number: 178623-11-5
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Absorption [λmax]: 579 ± 3 nm
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Emission [λmax]: 591 ± 3 nm
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Extinction Coefficient (ε): >106,000 M⁻¹·cm⁻¹
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Reactive Moiety: NHS ester (forms stable amide linkage with 1° amines)
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Solubility: Acetonitrile, DMF, DMSO
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Buffer System for Fluorescence Readings: Methanol
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Appearance: Violet solid (powder)
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Storage: −20 °C, dry and protected from light (especially in solution)
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Trade Names: Sulforhodamin 101 succinimidyl ester, TR-4-SE, Texas Red succinimidyl ester, single isomer
Application
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Fluorescent labeling of proteins, peptides, and oligonucleotides
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Red-channel fluorescence microscopy
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Flow cytometry (FACS) and fluorescence-based assays
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Bioconjugation workflows requiring NHS ester chemistry
