Table 5.1 Molecular Probes heterobifunctional crosslinkers.

Cat # Crosslinker
Thiol (R–SH)Amine (R–NH2)Azide * (R–N3)Alkyne *Photoreactive †
S1553succinimidyl acetylthioacetate (SATA) ‡XX   
S1534succinimidyl trans-4-(maleimidylmethyl) cyclohexane-1-carboxylate (SMCC) ‡XX   
S1531succinimidyl 3-(2-pyridyldithio)propionate (SPDP)XX   
E22471-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDAC) § X   
P6317N-((2-pyridyldithio)ethyl)-4-azidosalicylamide (PEAS; AET) ‡X   X
A25224-azido-2,3,5,6-tetrafluorobenzoic acid, succinimidyl ester (ATFB, SE) X  X
B1508benzophenone-4-maleimideX   X
B1526benzophenone-4-isothiocyanate X  X
B15774-benzoylbenzoic acid, succinimidyl ester X  X
I10188iodoacetamide azide *X  X 
I10189iodoacetamide alkyne *X X  
C10413Click-iT maleimide DIBO alkyne *X X  
A10280azido (PEO)4 propionic acid, succinimidyl ester * X X 
A10279alkyne, succinimidyl ester * XX  
C10414Click-iT succinimidyl ester DIBO alkyne * XX  
* Azides react with alkynes via the copper-catalyzed azide–alkyne cycloaddition reaction, as discussed in Click Chemistry—Section 3.1 (where these products are also described).
† Reacts nonspecifically with available sites upon UV illumination.
‡ These reagents contain cryptic thiols that are exposed by disulfide reduction (SPDP or PEAS) or deacetylation (SATA) and can be subsequently disulfide-coupled to other thiolated molecules or thioether-coupled to maleimides or iodoacetamides.
§ EDAC couples amines to carboxylic acids (Derivatization Reagents for Carboxylic Acids and Carboxamides—Section 3.4).