Crosslinkers contain at least two reactive ends to specific functional groups, such as primary amines and sulfhydryls on proteins and antibodies, enabling the covalent joining of or two or more biomolecules. Homobifunctional crosslinkers have the same reactive chemistry at both ends, while heterobifunctional crosslinkers have different reactive chemistries at each end. PEGylated crosslinkers have enhanced solubility, increased stability, reduced aggregation, and reduced immunogenicity.
SMCC is one of the most common heterobifunctional crosslinkers used for crosslinking one protein to another protein. One end of the SMCC reacts (via NHS ester) with amines (-NH2) found in the amino acid lysine and N-terminus, and the other end reacts (via maleimide) with the thiol groups (-SH) found in the amino acid cysteine. However, SMCC-modified protein is extremely unstable and often self-reactive since proteins often contain both amine and thiol groups that cause significant amount of homo-crosslinking. In addition, it is quite difficult and tedious to quantify the number of maleimide groups on a protein. AAT Bioquest has developed a convenient and effective crosslinking method to link two biomolecules with a high conjugation yield. Our Buccutite™ method uses one pair of crosslinkers: Buccutite™ MTA and Buccutite™ FOL. MTA is added to one protein, while FOL is added to another protein. Protein-protein cross-linking reaction is initiated by mixing Protein-1-Buccutite ™ MTA and Protein-2-Buccutite ™ FOL. This crosslinking reaction occurs under extremely mild neutral conditions without any catalyst required, and it is robust and efficient.