3,3’-Dithiobis(sulfosuccinimidyl Propionate)

DTSSP (3,3′-Dithiobis(sulfosuccinimidyl Propionate)) is a widely used thiol-cleavable, homobifunctional crosslinking reagent. It is highly water-soluble and impermeable to cell membranes, making it suitable for studying extracellular or cell-surface proteins. Structurally, DTSSP contains amine-reactive N-hydroxysulfosuccinimide (Sulfo-NHS) ester groups at both ends of an 8-atom spacer arm. The Sulfo-NHS esters selectively react with primary amines, such as lysine residues on proteins, under mildly basic conditions (pH 7–9), forming stable amide linkages. The central disulfide bond within the spacer arm is cleavable by reducing agents like Dithiothreitol (DTT), Tris(2-carboxyethyl)phosphine (TCEP), or 2-Mercaptoethanol (2-ME), allowing reversible crosslinking.

DTSSP is commonly employed to study protein-protein interactions on the cell surface. By crosslinking interacting proteins, even weak or transient interactions can be “fixed” for subsequent analysis. Additionally, DTSSP can be used to immobilize proteins on amine-coated surfaces and to generate bioconjugates for biochemical assays.

A closely related reagent is Dithiobis(succinimidyl Propionate) (DSP, Lomant’s Reagent), which also features NHS ester groups at both ends of an 8-atom spacer. The main distinction is that DSP is water-insoluble and membrane-permeable, allowing it to penetrate cells for the study of intracellular protein interactions. In contrast, DTSSP’s water solubility and membrane impermeability make it ideal for selective extracellular applications. Both reagents share similar chemical reactivity and crosslinking mechanisms, but their solubility and membrane permeability define their specific experimental uses.

References:

1. Staros, J.V. (1982) Biochemistry 21, 3950-3955.
2. Lee, W.T. abd Conrad, D.H. (1985) J. Immunol. 134, 518-525.
3. Ward, W.S., et al (1985) Biochemistry 24, 4429-4434.