CBTF

CBTF is a bifunctional crosslinker for amine-to-thiol coupling. The coupling can be performed with high selectivity in biological medium using mild reaction conditions. CBTF readily reacts with organic amines in basic conditions to produce APN-probes suitable for cysteine labeling.

CBTF (Sodium 4-((4-(cyanoethynyl)benzoyl)oxy)-2,3,5,6-tetrafluorobenzenesulfonate) is a heterobifunctional reagent. It bears a 3-arylpropionitrile (APN) group. CBTF can be prepared from 4-iodobenzoic acid. It participates in various amine-to-thiol coupling reactions. It participates in the synthesis of various antibody-dye conjugates. CBTF is widely used for antibody conjugation.

Standard protein labeling procedure (lysine labeling):

• Dissolve the protein in an appropriate buffer* with pH 7.5-9.0 (e.g. PBS) at 1-10mg/mL concentration.
• Apply the appropriate amount of the stock solution of the reagent (1-5 molar eq. per lysine residue).
• Incubate at room temperature for 2 hours.
• If necessary, purify the protein-APN conjugate using size exclusion chromatography or ultrafiltration.
• The conjugate can be readily coupled with thiol-containing substrates by incubating the components in aqueous buffer (pH 6.5-9.0) at ambient temperature for 2 hours.

Standard protein labeling procedure (cysteine labeling):

Dissolve the protein in the appropriate buffer* with pH 6.5-9.0 (e.g. PBS) at 1-10mg/mL concentration.
Apply the appropriate amount of the stock solution of the APN-labeled molecule (1-5 molar eq. per free cysteine residue).
Incubate at room temperature for 2 hours.
If necessary, purify the protein conjugate using size exclusion chromatography or ultrafiltration.

*Note: avoid amine- and thiol-containing buffers.