HTRF® Labeling reagents

A selection of HTRF donor and acceptor dyes tailored for biomolecule labeling and straightforward assay development.

HTRF labeling reagents and kits are a do-it-yourself solution for labeling biomolecules with HTRF fluorescent dyes or DNP tag.

These reagents are ideal for experienced users familiar with labeling and chromatography. The availability of two different donor chemistries, i.e. Europium- or Terbium-based, as well as various functional groups on Eu3+ cryptate and XL665, adds significant flexibility to labeling strategies and assay design.

Besides standard labeling procedures with HTRF dyes, SNAP-tag® technology allows a targeted labeling at the C- or N-terminus of proteins. This platform is an original and efficient way to accurately label a protein of interest on a targeted site. For more information about labeling of encoded proteins with Lumi4®-Tb cryptate or with acceptor dyes, see our Tag-lite® section.

If a do-it-yourself solution isn't for you, Cisbio Bioassays' labeling experts are available to advise you, through our custom labeling service.

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Assay Principle

HTRF fluorophore labeling reagents are for use with standard protein chemistry protocols, such as SMCC/SPDP coupling. As shown here, preactivation of both the label and the biomolecule may be required. Recovery of labeled material can be achieved using conventional chromatographic methods, such as gel filtration or HPLC. The purification devices required for recovering labeled material are not delivered with these reagents.

Product Performance & specification

Europium Trisbipyridine Cryptate (Eu3+-TBP Cryptate) is available from Cisbio Bioassays in microgram to milligram quantities for use by customers in biomolecule labeling. The cryptate is available with 3 different functional groups


Di-amino Cryptate (Eu3+-TBP-NH2 Cryptate), for use in combination with bi-functional reagents such as carbodiimides and SMCC/SPDP, for a flexible labeling solution.


N-hydroxysuccinimide activated Cryptate (Eu3+-TBP-NHS Cryptate), reacts with primary amines. This specific Cryptate is available either by itself or in thecryptate labeling kit.


Maleimide activated Cryptate (Eu3+-TBP-MP Cryptate), enabling specific labeling of thiol groups.

XL665 Reagents

Cross-linked allophycocyanin, XL665, is available either with an amine group (XL665-NH2) or a maleimide group (XL665-maleimide) for simplified conjugation.

DNP Chemical Tag

DNP (2,4-dinitrophenyl) is a small organic tagging alternative to biotin. It can be detected using an anti-DNP antibody (see HTRF toolbox reagents). The DNP-NHS labeling reagent enables conjugation of DNP by targeting primary amino-groups (N-terminus or lysine residues) under very mild conditions.

Part#, inserts & MSDS

Ordering Info

DescriptionCat. noProduct insertMSDS
DNP-NHS - 0.2 mg65DNSABD
Europium cryptate NH2 - 0.1 mg65EU2ABA
Europium cryptate NH2 - 1 mg65EU2ABB
Europium cryptate TBP Maleimide - 0.1 mg65EUMABA
Europium cryptate TBP Maleimide - 1 mg65EUMABB
Europium cryptate TBP NHS - 0.1 mg65EUSABA
Europium cryptate TBP NHS - 1 mg65EUSABB
XL665 NH2 - 1 mg65XL2ABB
XL665 NH2 - 10 mg65XL2ABC
XL665 Maleimide - 1 mg65XLMABB
XL665 Maleimide - 10 mg65XLMABC