Protein Modification Reagents
STEMCELL Technologies Papain, Size: 25 mg
Papain is a cysteine protease consisting of a single polypeptide containing three disulfide bridges. Native crystalline papain is unreactive until acted upon by mild reducing agents, e.g., cysteine, sulfide, or sulfite, and therefore likely exists as a zymogen. Papain has a wide specificity with a preference towards arginine, lysine, and phenylalanine. This enzyme degrades protein substrates such as the intercellular matrices of cartilage more extensively than pancreatic proteases and is typically less damaging and more effective than other proteases for tissue dissociation applications (Huettner & Baugham; Lam) and has also been used for the digestion of neural tissue (Fasano et al.).
Medchemexpress LLC DBCO-NHCO-PEG2-maleimide | 2698339-31-8 | 97.7% | C32H34N4O7 | 10MG
DBCO-NHCO-PEG2-maleimide is a bifunctional click-chemistry linker that couples a dibenzocyclooctyne (DBCO) moiety for strain-promoted alkyne-azide cycloaddition (SPAAC) with a maleimide group for thiol-selective conjugation. The PEG2 spacer improves solubility and flexibility, making it suitable for bioconjugation and linker synthesis.
- Enables copper-free SPAAC click chemistry
- Provides thiol-selective maleimide conjugation
- PEG2 spacer improves aqueous solubility
- Suitable for bioconjugation and linker synthesis
- High reported purity (~97.7%)
- Stable as powder at -20°C for long-term storage
Sigma Aldrich Fine Chemicals Biosciences Trypsin from bovine pancreas TPCK Treated, essentially salt-free, lyophilized powder, >=10,000 BAEE units/mg protein | 9002-07-7 | MFCD00082094 | 100MG
Trypsin from bovine pancreas TPCK Treated, essentially salt-free, lyophilized powder, >=10,000 BAEE units/mg protein | 9002-07-7 | MFCD00082094 | 100MG
Medchemexpress LLC DSPE-PEG-maleimide | 00-00-0 | 99.5% | 10MG
DSPE-PEG-maleimide (MW 5000) is a pegylated phospholipid that combines a DSPE lipid anchor with a PEG spacer terminated in a maleimide group for selective thiol conjugation. Supplied as a solid powder with high purity, it is designed for incorporation into liposomes and lipid nanoparticles and for attaching thiol-containing ligands and peptides to particle surfaces.
- Molecular weight ~5,000 for predictable spacer length.
- Maleimide functional group enables selective thiol conjugation.
- DSPE lipid anchor allows stable insertion into lipid bilayers.
- PEG spacer increases circulation time and stability of formulations.
- High purity (~99.5%) suitable for research and formulation work.
- Powder form with recommended storage at -20°C for long-term stability.
Medchemexpress LLC PC-biotin-PEG4-NHS carbonate | 2055198-03-1 | 97.0% | C35H50N6O14S | 10MG
PC-Biotin-PEG4-NHS carbonate is a PEG-based photocleavable biotinylation reagent bearing an NHS carbonate amine-reactive group. It is designed for use as a PROTAC linker or to introduce a light-cleavable biotin tag for biochemical conjugation, affinity capture, and downstream light-mediated release of labeled molecules.
- Photocleavable biotin enables light-controlled release of captured molecules.
- PEG4 spacer improves solubility and reduces steric hindrance in conjugates.
- NHS carbonate reacts with primary amines to form stable carbamate linkages.
- High reported purity supports use in synthesis and analytical workflows.
- Powder storage at -20°C and cold-solvent storage extend compound stability.
Medchemexpress LLC Biotin-peg6-mal | 1808990-66-0 | 99.0% | C31H51N5O11S | 10MG
Biotin-PEG6-Mal is a biotin-labeled polyethylene glycol (PEG6) maleimide linker that enables thiol-selective conjugation to introduce a biotin affinity tag for capture or detection using streptavidin/avidin systems. It is commonly used in PROTAC assembly and bioconjugation workflows where solubility and specific thiol reactivity are required.
- Thiol-selective maleimide group for rapid, specific conjugation.
- PEG6 spacer improves solubility and reduces steric hindrance.
- Biotin affinity tag enables high-affinity streptavidin/avidin capture.
- High purity supports reproducible experimental results.
- Stable as a powdered reagent with defined cold-storage recommendations.
Medchemexpress LLC Biotinyl-NH-PEG3-C3-amido-C3-COOH | 1202761-21-4 | 99.3% | 50 MG
Biotinyl-NH-PEG3-C3-amido-C3-COOH is a PEG-based PROTAC linker that can be used in the synthesis of PROTACs. It is for research use only and not sold to patients.
- Solid appearance
- White to off-white color
- Soluble in DMSO (250 mg/mL)
- Soluble in methanol (≥ 100 mg/mL)
- Molecular weight: 560.70
- Molecular formula: C25H44N4O8S