Btk inhibitor 1 R enantiomer

Target: This ligand targets Bruton tyrosine kinase (BTK) in biochemical or cellular target-engagement studies.

Mechanism of Action: Used as the target-protein recognition element, this ligand provides the binding interface for Bruton tyrosine kinase (BTK). In PROTAC design, a derivatizable position on the ligand can be connected through an optimized linker to an E3 ligase ligand, such as a CRBN, VHL, or IAP recruiter, while preserving productive target engagement. The resulting bifunctional molecule brings Bruton tyrosine kinase (BTK) into proximity with the recruited E3 ligase, enabling ternary-complex formation. If the complex has favorable geometry and residence time, target lysine ubiquitination is promoted, leading to proteasome-dependent degradation in experimental systems.

• BTK-Directed PROTAC Degradation: The Btk inhibitor 1 R enantiomer can be used as a high-affinity ligand module to build PROTACs that recruit an E3 ligase and drive selective BTK ubiquitination. This enables targeted protein degradation studies to quantify loss of BTK protein levels, downstream signaling suppression, and dependence on the recruited ubiquitin-proteasome pathway.

• Enantiomer-Specific Binding Optimization: Using the R enantiomer supports PROTAC design where stereochemistry governs binding geometry and ternary complex stability. Researchers can compare R- versus S-based PROTACs to identify which configuration yields improved BTK engagement, stronger ubiquitination efficiency, and more potent degradation kinetics in cellular models.

• Pathway Dissection via BTK Knockdown: PROTACs incorporating this BTK ligand can be applied to dissect BTK-dependent signaling networks by achieving degradation rather than transient inhibition. This approach helps distinguish effects of BTK removal from catalytic blockade, enabling mechanistic studies of B-cell receptor signaling, phosphorylation cascades, and compensatory responses.

• Systematic E3 Ligase Recruitment Studies: The ligand can be paired with different E3 ligase recruiters to evaluate how ligase choice influences BTK degradation potency and selectivity. By varying linker length and recruiter identity, experiments can map structure–activity relationships that control ternary complex formation and BTK turnover rates.

• Proteome-Selective Degradation Profiling: PROTAC constructs built from the Btk inhibitor 1 R enantiomer can be used to assess degradation selectivity across related kinases. Targeted and global proteomics can determine whether BTK is preferentially degraded, quantify off-target degradation events, and refine design rules for achieving high specificity in targeted protein degradation workflows.

Btk inhibitor 1 R enantiomer is a BTK kinase target ligand intended for use as the target-engaging component or reference ligand in PROTAC discovery workflows. Its known small-molecule recognition profile enables rational linker-vector evaluation and comparative degrader design. This molecule is described in detail below.

Structure: The structure of Btk inhibitor 1 R enantiomer is characterized by primary or secondary amine/basic nitrogen centers; heteroaromatic protein-recognition scaffold. These features provide defined hydrogen-bonding, hydrophobic, and steric elements that can support affinity retention while enabling analogue-based linker-vector selection.

Reactivity: The amine/basic nitrogen-containing motif can be evaluated for acylation, sulfonylation, alkylation, or carbamate/urea linker installation when that vector is solvent exposed. For PROTAC construction, the POI ligand can be paired with CRBN ligands such as thalidomide, pomalidomide, or lenalidomide analogues, VHL ligands such as VH032 derivatives, or less common IAP/MDM2/cIAP-recruiting ligands, with alkyl, PEG, piperazine, triazole, or amide linkers screened for ternary-complex formation. In practice, incorporation into PROTACs should begin from derivatives that preserve the reported binding pharmacophore, followed by systematic variation of linker length, polarity, rigidity, and exit-vector geometry to optimize target engagement, E3 recruitment, and cellular degradation readouts.