SDA (NHS-Diazirine) (succinimidyl 4,4'-azipentanoate)

Thermo Scientific Pierce SDA (NHS-Diazirine) combines proven NHS-ester and diazirine-based photoreaction chemistries with conjugate amine-containing molecules with nearly any other functional group via long-wave UV-light activation. A 3.9Å spacer arm separates the two photoreactive groups.

Features of SDA (NHS-Diazirine):

• Membrane-permeable—suitable for in vivo intracellular protein crosslinking
• Heterobifunctional—NHS ester group reacts with primary amines at pH 7 to 9 to form covalent amide bonds; diazirine (azipentanoate) group reacts efficiently with any amino acid side chain or peptide backbone upon activation with long-wave UV light (330-370 nm)
• Controllable—two-step chemical crosslinking is activated using common laboratory UV lamps
• Easy to use—these crosslinkers are photo-stable under typical laboratory lighting conditions so there is no need to perform experiments in the dark
• Better than aryl azides—the diazirine photoreactive group has better photostability in normal light than phenyl azide groups of traditional photoreactive crosslinkers, yet the diazirine group is more efficiently activated by long-wave UV light

Succinimidyl-diazirine (SDA) reagents are a new class of crosslinkers that combine proven amine-reactive chemistry with an innovative and efficient diazirine-based photochemistry for conjugating amine-containing molecules to nearly any other functional group. The SDA crosslinkers include six compounds differing in spacer arm lengths, ability to cleave the crosslinked proteins, and presence or absence of a charged group for membrane permeability. Protein crosslinking is an important technique used to understand protein structure and to stabilize protein-protein interactions, and these SDA reagents extend the efficiency and range of interactions that can be explored by this approach.

Typical bifunctional amine- or sulfhydryl-reactive crosslinkers require specific amino acid groups (e.g., lysine or cysteine) at the correct distance on both proteins to capture protein interactions. The SDA crosslinkers circumvent this limitation by allowing specific labeling of one protein using the amine-reactive N-hydroxysuccinimide (NHS) ester followed by UV-activated crosslinking via the diazirine moiety to any amino acid side chain or peptide backbone of a second protein. Diazirine-based photocrosslinkers have better photostability than phenyl azide-based photocrosslinkers and are easily activated with long-wave UV light (330-370nm).

Multiple Diazirine Crosslinkers Available
The NHS-ester diazirine derivatives (SDA, LC-SDA and SDAD) lack a charged group and are membrane-permeable. This property makes them ideal for intracellular and intramembrane conjugations. By contrast, Sulfo-SDA, Sulfo-LC-SDA and Sulfo-SDAD contain negatively charged sulfate groups that improve their water solubility and reduce cell membrane permeability, enabling their use for extracellular protein crosslinking. SDAD and Sulfo-SDAD also have a disulfide bond within the spacer that can be cleaved with reducing agents.

• Short (3.9Å) and long (12.5Å) spacer arm varieties
• Membrane-permeable (NHS) and impermeable (Sulfo-NHS) varieties
• Non-cleavable and cleavable (disulfide spacer) varieties

Related Products
Sulfo-SDA (Sulfo-NHS-Diazirine)
LC-SDA (NHS-LC-Diazirine)
SDAD (NHS-SS-Diazirine)