Labelling

IC<sub>5<sub>-OSu special packaging is ued as fluorescent labeling reagent. IC5 is an indocyanine dye that can react with amine groups on proteins, peptides, and amine-modified oligonucleotides. Due to the absence of a sulfonate group in its structure, the water-solubility of the molecules is very low, necessitating the use of an organic solvent for dissolution. Furthermore, as no negative charge is added to the protein, the total number of charges on the modified protein remains the same before and after labeling with these compounds.

Biotin-(AC<sub>5<sub>)<sub>2<sub>-OSu is utilized as the biotin labeling agent in the Biotin Labeling Kit-NH<sub>2<sub>.

Cy7.5 NHS ester is a water soluble fluorescent dye with a terminal NHS ester group. Cy7.5 NHS ester is a near-infrared (NIR) dye known for its long-wave emission. It serves as an amine-reactive derivative, ideal for labeling biomolecules like proteins and peptides for in vivo NIR imaging.

Ald-Ph-PEG8-t-butyl ester is a PEG linker containing a benzaldehyde and a t-butyl ester. The aldehyde group is a versatile electrophile that is reactive towards amines, hydroxylamines, and hydrazines while the t-butyl ester can be removed to reveal a carboxylic acid that can react with alcohols or amines.

BP Fluor 647 NHS Ester is a very popular amine-reactive fluorescent dye which can be used to label antibody, protein, and other biomolecules. BP Fluor 647 is a red fluorescent dye with excitation and emission maxima at 648 nm and 671 nm respectively.

DNP-PEG12-azide is a heterobifunctional PEG linker featuring a dinitrophenyl and a primary amine. Dinitrophenyl is an excellent FRET quencher pair with tryptophan or tyrosine, while the azide can be used in click chemistry with terminal alkynes or strained cyclooctynes.

Fluorescein-PEG12-amine, TFA salt is a PEG linker containing an amine and a fluorescein dye. Primary amines readily form amides with carboxylic acids in the presence of reagents such as HATU or EDC while fluorescein is a fluorophore is a near-UV/Vis spectrum dye that can be used for in vivo fluorescence assays such as FRET.

2,3,4-(PEG4-Azide)-1-(PEG4-Amine)methane is a four-armed PEG reagent that combines three azide groups with a primary amine. Azides are frequently used in click reactions with terminal alkynes, DBCO and BCN moieties to form stable triazole linkages with the target molecule. Primary amines are useful scaffolds for easily building complexity such as in making amides, building heterocycles, and performing SNAr reactions on electron-deficient aromatic compounds. PEG linkers increase a molecule’s water solubility and their use impacts a compound’s ADME properties in vivo.

Fluorescein-PEG12-Mal is a PEG linker containing a maleimide and a fluorescein dye. Maleimide is a thiol-specific covalent linker which is used to label cysteine residues in proteins while fluorescein is a fluorophore is a near-UV/Vis spectrum dye that can be used for in vivo fluorescence assays such as FRET.