What defines a heterobifunctional crosslinker?

A heterobifunctional crosslinker is defined by having different functional groups that can react with proteins. This unique structure allows the crosslinker to form connections between different molecules (usually proteins) through interactions with their respective functional groups. This property is particularly useful in biochemistry and molecular biology for various applications, such as probing protein interactions, creating multi-protein complexes, or stabilizing protein structures.

The key aspect of this type of crosslinker is that the presence of two distinct functional groups enables selective reaction with different sites on proteins, facilitating versatile bioconjugation strategies. This differentiation can lead to the formation of engineered protein networks with specific characteristics or functionalities.

While other options mention aspects of crosslinkers, they do not capture the essential feature of heterobifunctionality, which is the combination of different reactive groups that allows for diverse interactions with biomolecules.