Amine-to-sulfhydryl heterobifunctional protein crosslinking reagents are for conjugation between primary amine (lysine) and sulfhydryl (cysteine) groups in proteins and other molecules. These reagents are available with different lengths and types of spacer arms, such as NHS-haloacetyl, NHS-maleimide, and NHS-pyridyldithiol crosslinkers.

Our amine-to-sulfhydryl crosslinkers have the following characteristics:

  • NHS-haloacetyl crosslinkers are based on NHS ester and iodoacetyl, bromoacetyl, or other haloacetyl reactive groups
  • NHS-maleimide crosslinkers are based on N-hydroxysuccinimide and maleimide reactive groups; includes sulfo-SMCC and forms contain long, polyethylene glycol (PEG) spacer arms
  • NHS-pyridyldithiol crosslinkers are based on N-hydroxysuccinimide and pyridyldithiol reactive groups; a disulfide bond renders the crosslink (spacer arm) cleavable with reducing agents.

Featured amine-to-sulfhydryl crosslinkers

Often used to probe the interactions between biomolecules, this heterobifunctional crossslinker covalently links succinimidyl ester chemically with primary amines. 

Our controlled protein-protein crosslinking kit contains sulfo-SMCC crosslinker, modification reagents, and buffers for conjugating antibodies, enzymes, and other purified proteins needed as probes. 

This heterobifunctional  crossslinker, often used for examining spatial relationships between biomolecules, covalently links a succinimidyl ester with primary amines, while  the maleimide group can react with available thiols. 

Choose the right amine-to-sulfhydryl crosslinker for your experiment

Amine-to-Sulfhydryl Crosslinkers Products Spacer Arm (Å) Cleavable? Water-soluble? Membrane permeable?
NHS-Haloacetyl Crosslinkers SIA 1.5 N/A No Yes
SBAP 6.2  N/A No Yes
SIAB 10.6  N/A No Yes
Sulfo-SIAB 10.6  N/A Yes No
NHS-Maleimide AMAS 4.4 N/A No Yes
BMPS 5.9 N/A No Yes
GMBS 7.3 N/A No Yes
Sulfo-GMBS 7.3 N/A Yes No
MBS 7.3 N/A No Yes
Sulfo-MBS 7.3 N/A Yes No
SMCC 8.3 N/A No Yes
Sulfo-SMCC 8.3 N/A Yes No
EMCS 9.4 N/A No Yes
Sulfo-EMCS 9.4 N/A Yes No
SMPB 11.6 N/A No Yes
Sulfo-SMPB 11.6 N/A Yes No
SMPH 14.2 N/A No Yes
LC-SMCC 16.2 N/A No Yes
Sulfo-KMUS 16.3 N/A No Yes
NHS-Pyridyldithiol Crosslinkers SPDP 6.8 Thiol No Yes
LC-SPDP 15.7 Thiol No Yes
Sulfo-LC-SPDP 15.7 Thiol Yes No
SMPT 11.2 Thiol No Yes
PEG4-SPDP 25.7 Thiol Yes No
PEG12-SPDP 54.1 Thiol Yes No

N/A: No cleavage sites available

SM(PEG)n NHS-PEG-maleimide crosslinkers

The N-hydroxysuccinimide ester (NHS) group reacts specifically and efficiently with lysine and N-terminal amino groups at pH 7-9 to form stable amide bonds. The maleimide group reacts with reduced sulfhydryls at pH 6.5-7.5 to form stable thioether bonds.

Products Molecular weight Spacer Arm (Å) Cleavable? Water-soluble? Membrane permeable?
SM(PEG)2 425.39 17.6 N/A Yes No
SM(PEG)4 513.5 24.6 N/A Yes No
SM(PEG)6 601.6 32.5 N/A Yes No
SM(PEG)8 689.71 39.2 N/A Yes No
SM(PEG)12 865.92 53.4 N/A Yes No
SM(PEG)24 1394.55 95.4 N/A Yes No

N/A: No cleavage sites available

Protein quantitation immunoassays
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