DiAzKs Hydrochloride: Properties, Preparation & Application Protocol

DiAzKs hydrochloride is a diazo-functionalized lysine analogue designed for site-specific incorporation into proteins via amber suppression, enabling covalent crosslinking and bioorthogonal labeling in genetic code expansion workflows.

Product Name

DiAzKs hydrochloride

SKU

D656555

Compound Class

Diazo-functionalized unnatural amino acid (lysine analogue)

Primary Application

Genetic code expansion; site-specific protein labeling via amber suppression

Recommended Storage

Store at −20 °C, protected from light and moisture

Solvent Compatibility

Soluble in water or DMSO (verify concentration by absorbance or mass)

Overview and Mechanism of Action

DiAzKs hydrochloride is a synthetic, diazo-bearing lysine analogue developed for use in genetic code expansion (GCE) systems. The compound contains a reactive diazo group (–C(=N₂)–) appended to the lysine side chain, which enables highly selective bioorthogonal reactions with carboxylic acid partners under mild conditions, making it valuable for covalent protein–protein and protein–nucleic acid crosslinking studies.

In GCE workflows, DiAzKs is recognized and charged onto an engineered pyrrolysyl-tRNA synthetase (PylRS)/tRNA^Pyl pair, allowing its co-translational insertion at amber (UAG) stop codons introduced by site-directed mutagenesis. Once incorporated, the diazo group can participate in carbene-mediated insertion reactions or react with proximal nucleophiles, enabling proximity-dependent covalent capture of interacting biomolecules.

The hydrochloride salt form improves aqueous solubility compared with the free base, facilitating direct supplementation into cell culture media or in vitro translation reactions.

Stock Solution Preparation

Follow the steps below to prepare a working stock solution of DiAzKs hydrochloride:

1. Determine target concentration: A stock concentration of 100–500 mM is typical for supplementation into culture media at a final concentration of 0.1–2 mM. Adjust based on your experimental design.
2. Select solvent: DiAzKs hydrochloride is reported to be soluble in water and DMSO. For aqueous stocks, use sterile phosphate-buffered saline (PBS, pH 7.4) or ultrapure water. If using DMSO, ensure the final DMSO concentration in assay media does not exceed 0.1% (v/v) to avoid cytotoxicity.
3. Dissolve the compound: Weigh the required amount of DiAzKs hydrochloride into a clean, dry microcentrifuge tube under amber light or in subdued lighting. Add the calculated volume of solvent, vortex gently for 30–60 seconds, and sonicate briefly (30 s, room temperature) if complete dissolution is not achieved.
4. Filter-sterilize: Pass the stock solution through a 0.22 µm syringe filter before addition to cell culture.
5. Verify concentration: Confirm stock concentration by UV-Vis absorbance (if compound has a defined extinction coefficient) or by analytical methods appropriate to your laboratory.
6. Aliquot and store: Divide into single-use aliquots to avoid freeze-thaw cycles. Store at −20 °C, protected from light. Note that diazo groups can be sensitive to heat, strong light, and acidic conditions; minimize unnecessary exposure.

Note: Specific solubility values and extinction coefficients are not confirmed in the current source material; consult the certificate of analysis (CoA) supplied with the product or contact Aladdin Scientific technical support.

Experimental Application Protocol

The following general protocol describes incorporation of DiAzKs hydrochloride into a protein of interest via amber suppression in mammalian cells. Adapt as needed for bacterial or cell-free systems.

Materials Required

• DiAzKs hydrochloride stock solution (prepared as above)
• Expression plasmid encoding the gene of interest with UAG amber codon at the desired site
• Plasmid encoding an orthogonal PylRS variant evolved to accept DiAzKs, and its cognate tRNA^Pyl
• Mammalian cell line of choice (e.g., HEK293T)
• Complete growth medium (e.g., DMEM + 10% FBS)
• Transfection reagent

Procedure

1. Cell seeding: Seed cells at appropriate density (e.g., 2 × 10⁵ cells/well in a 6-well plate) 18–24 h before transfection.
2. Transfection: Co-transfect the amber-codon-containing expression plasmid and the orthogonal PylRS/tRNA^Pyl plasmid using the manufacturer's recommended protocol for your transfection reagent.
3. Compound addition: At the time of transfection (or immediately after), supplement the culture medium with DiAzKs hydrochloride to a final concentration of 0.25–1 mM (optimize empirically). Replace medium with fresh DiAzKs-containing medium every 24 h.
4. Expression period: Allow protein expression for 24–48 h at 37 °C, 5% CO₂.
5. Crosslinking or labeling: If performing photo- or chemically-induced crosslinking, follow the specific conditions required for diazo reactivity (e.g., UV irradiation, addition of reaction partner). Carry out under conditions validated for your biological system.
6. Harvest and analysis: Lyse cells under appropriate conditions. Analyze protein expression and unnatural amino acid incorporation by SDS-PAGE, Western blot, or mass spectrometry. Full-length protein production in the absence of DiAzKs serves as a negative control.

Optimization note: Optimal DiAzKs concentration, expression time, and PylRS variant should be determined empirically for each protein target. Consult published literature on DiAzKs or closely related diazo-lysine analogues for guidance.

Storage, Stability & Safety Considerations

Storage: Store DiAzKs hydrochloride at −20 °C in a tightly sealed container, protected from light and moisture. Under these conditions, the compound is expected to be stable for the duration indicated on the product certificate of analysis.

Stability: Diazo functional groups are inherently reactive species. DiAzKs hydrochloride should be handled with care to avoid exposure to strong acids, strong bases, elevated temperatures, or prolonged UV/visible light, all of which can decompose the diazo moiety and reduce compound efficacy. Prepare fresh working solutions where possible and avoid repeated freeze-thaw cycles by working from small aliquots.

Safety: As with all research chemicals, handle DiAzKs hydrochloride in accordance with good laboratory practice. Wear appropriate personal protective equipment (PPE) including lab coat, nitrile gloves, and eye protection. Consult the Safety Data Sheet (SDS) for this product before use. Diazo compounds may be reactive and should be handled away from open flames. Dispose of waste according to local institutional and regulatory guidelines.

Note: A product-specific SDS and CoA should accompany each shipment. Contact Aladdin Scientific customer service if these documents are not received.

Troubleshooting

• Low or no full-length protein expression: Confirm that the PylRS variant used is evolved or reported to accept DiAzKs. Verify plasmid integrity by sequencing. Increase DiAzKs concentration stepwise (up to 2 mM) and ensure compound is dissolved completely.
• Compound does not dissolve: Warm gently to 37 °C (do not boil) and vortex. If aqueous solubility is insufficient, prepare a DMSO master stock and dilute into aqueous buffer. Keep final DMSO below 0.1% (v/v) in cell-based assays.
• Reduced crosslinking efficiency: Diazo reactivity may have been lost due to compound degradation. Use a freshly prepared aliquot and verify storage conditions. Optimize irradiation time and intensity for photocrosslinking applications.
• High background or non-specific crosslinks: Include a negative control lacking the amber codon in the gene of interest. Optimize DiAzKs concentration and reaction time to minimize non-specific events.
• Cell toxicity at high concentrations: Reduce DiAzKs concentration and use shorter supplementation windows. Assess DMSO contribution if DMSO-based stocks are used.

Frequently asked questions

What is DiAzKs hydrochloride used for?

DiAzKs hydrochloride is a diazo-functionalized lysine analogue used primarily in genetic code expansion experiments. It is incorporated into proteins site-specifically via amber suppression using an engineered PylRS/tRNA pair, enabling bioorthogonal covalent crosslinking and proximity labeling of protein interaction partners.

What solvent should I use to dissolve DiAzKs hydrochloride?

DiAzKs hydrochloride can be dissolved in water (e.g., sterile PBS or ultrapure water) or DMSO. Aqueous solvents are preferred for direct addition to cell culture. If DMSO is used as the primary solvent, dilute the stock thoroughly to keep the final DMSO concentration below 0.1% (v/v) in cell-based experiments. Always consult the product CoA for confirmed solubility data.

How should DiAzKs hydrochloride be stored to maintain stability?

Store DiAzKs hydrochloride at −20 °C in a sealed container, away from light, heat, and moisture. Aliquot the stock solution into single-use volumes to avoid repeated freeze-thaw cycles. Diazo groups are sensitive to decomposition under acidic conditions, elevated temperatures, and UV/visible light, so minimizing exposure to these conditions is critical for maintaining compound integrity.

Which PylRS variant should I use to incorporate DiAzKs into my protein of interest?

You should use a pyrrolysyl-tRNA synthetase (PylRS) variant that has been evolved or reported to specifically recognize and charge DiAzKs onto its cognate tRNA. Consult the primary literature describing DiAzKs or closely related diazo-lysine analogues to identify the appropriate PylRS variant for your expression system. Aladdin Scientific technical support can also assist with application guidance.

Is DiAzKs hydrochloride safe to handle in standard laboratory conditions?

DiAzKs hydrochloride should be handled following standard laboratory safety protocols. Wear appropriate PPE including a lab coat, nitrile gloves, and safety glasses. Diazo compounds can be reactive; avoid exposure to open flames, strong acids, and excessive heat. Always review the product-specific SDS before use and dispose of waste according to institutional guidelines.

References

1. Aladdin Scientific product page: DiAzKs hydrochloride, SKU D656555. Aladdin Scientific.
2. MedChemExpress (MCE) product reference: HY-D0853A, DiAzKs hydrochloride. MedChemExpress.
3. Chin JW. Expanding and reprogramming the genetic code. Nature. 2017;550(7674):53-60. doi:10.1038/nature24031
4. Meineke B, Heimgaertner J, Aloisi C, et al. Genetic encoding of diazo groups for proximity-induced diazo transfer reactions in living cells. [Publication details require verification]

Products are supplied for research and development use only. Not for use in humans, animals, diagnosis, or therapy.