MB™ 543 is a very hydrophilic, water-soluble orange fluorescent dye. Structurally related to Alexa Fluor® 546 dye, MB™ 543 dye contains an additional, negatively charged sulfo group (SO3H) to improve water solubility and minimize self-quenching. Characteristic features of MB™ 543 are strong absorption, high fluorescence quantum yield, high photostability, and pH insensitivity from pH 3 to pH 10. MB™ 543 is a highly suitable dye for single-molecule detection applications and high-resolution microscopy such as PALM, dSTORM, STED etc.
MB 543 Picolyl Azide is an advanced probe that incorporates a copper-chelating motif to raise the effective concentration of Cu(I) at the reaction site. The rate of CuAAC reaction depends on concentrations of all reagents, including copper, thus the raise of the effective copper concentration at the reaction site dramatically increase the rate of CuAAC reaction without the need to increase concentration of azide reagent and copper.
In addition, the use of picolyl azide instead of conventional azide allows for at least a tenfold reduction in the concentration of the copper catalyst without sacrificing the efficiency of labeling.
In summary, the introduction of a picolyl moiety into an azide probe leads to a substantial increase in the sensitivity of alkyne detection. This will be of special value for the detection of low abundance targets or where significant increase in signal intensity is desired.