Bis-Mal-PEG5
Bis-Mal-PEG5 is a bifunctional, heterobifurcating polyethylene glycol linker bearing two maleimide reactive groups, enabling efficient thiol–maleimide conjugation chemistry. Structurally, it consists of a short PEG chain that spaces the two electrophilic maleimide termini, providing a flexible, hydrophilic spacer that can reduce steric constraints and improve the accessibility of attachment sites on PROTAC components. In PROTAC design, Bis-Mal-PEG5 is used to connect or functionalize ligands or other molecular modules that present accessible cysteine/thiol handles, thereby generating defined, stable thioether linkages under mild conditions. The bis-maleimide format supports multivalent architectures, such as bridging two thiol-bearing fragments to tune effective molarity, linker length, and overall conjugate geometry. This makes it a practical tool for constructing and optimizing targeted protein degradation probes, where controlled conjugation and minimized nonspecific interactions are critical for reproducible degradation activity.
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* For research and manufacturing use only. Not for human or clinical use.
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Bis-Mal-PEG5 is a bifunctional, PEG-based linker designed for constructing PROTACs and other targeted protein degradation conjugates by enabling efficient attachment of two ligands through maleimide reactivity. Its flexible ethylene glycol segments improve solubility and conformational adaptability, which can help maintain productive geometry for ternary complex formation. This product is commonly used to generate well-defined, dual-ligand architectures; detailed structural and reactivity considerations are provided below.
Structure: The linker is a bis-maleimide functionalized polyethylene glycol scaffold, providing two electrophilic maleimide groups connected via a flexible PEG chain. It contains carbon–carbon and carbon–oxygen framework bonds typical of PEG, with conjugated alkene functionalities in the maleimide rings. The PEG segment imparts hydrophilicity and conformational flexibility.
Reactivity: Maleimide groups undergo selective Michael-type addition with thiols (such as cysteine residues or reduced thiol-containing ligands) to form stable thioether linkages. PROTAC assembly is typically performed under mildly basic, aqueous-compatible conditions to promote thiol availability while preserving maleimide integrity. Common approaches use buffered aqueous solvents and controlled stoichiometry; no metal catalysts are generally required, and reaction progress is monitored by analytical methods.
* Our calculator is based on the following equation:
Concentration (start) x Volume (start) = Concentration (final) x Volume (final)
It is commonly abbreviated as: C1V1 = C2V2
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