ATTO 550 Tetrazine

• Ex/Em: 553/574 nm
• Extinction coefficient: 120,000 cm^-1M^-1
• Reactive group: Tetrazine
• Click Chemistry Conjugation: Provides rapid and copper-free labeling of TCO-modified biomolecules
• High Quantum Yield & Stability: Provides intense fluorescence with high photostability and thermal stability
• Cationic Nature: Retains a net +1 charge upon conjugation

ATTO 550 is an orange fluorescent dye chemically related to the well-known Rhodamine 6G and Rhodamine B dyes. It is characterized by a strong absorption, a high fluorescence quantum yield, and excellent photostability and thermal stability. This dye exhibits moderate hydrophilicity, with an optimal excitation range of 540-565 nm. ATTO 550 is cationic and carries a net electrical charge of +1 after coupling to a substrate. This dye is well-suited for advanced applications in single-molecule detection and high-resolution microscopy techniques, including PALM, dSTORM, and STED microscopy. It is also compatible with flow cytometry (FACS), fluorescence in situ hybridization (FISH), and a variety of other biological assays. ATTO 550 can be used with excitation sources and fluorescence filters similar to those for Cy3® and TAMRA.

ATTO 550 tetrazine is particularly useful for labeling TCO-modified biomolecules under copper-free conditions. It reacts with TCO-functionalized molecules, forming a stable conjugate via a dihydropyrazine moiety. This click reaction is favored over others due to its extremely fast kinetics and higher yields under mild reaction conditions, making it a popular choice for researchers.