Bicyclobutane carboxylic amide as a cysteine-directed strained electrophile for selective targeting of proteins

2021 Fiscal Year Final Research Report

• Project/Area Number: 19H02854
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 37030:Chemical biology-related
• Research Institution: Kyushu University
• Principal Investigator: Shindo Naoya 九州大学, 薬学研究院, 助教 (20722490)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: コバレントドラッグ / ビシクロブタン / システイン / タンパク質 / 不可逆阻害剤

Outline of Final Research Achievements

In this study, we introduced bicyclobutane (BCB) carboxylic amide as a new class of thiol-reactive electrophiles for irreversible inhibition of targeted proteins. The strain-driven nucleophilic addition to BCB amides proceeded chemoselectively with cysteine under neutral aqueous conditions, the rate of which was significantly slower than that of acrylamide. This reactivity profile of BCB amide was successfully exploited to develop covalent ligands targeting BTK. By tuning BCB amide reactivity and optimizing its disposition on the ligand, we obtained a selective covalent inhibitor of BTK. The in-gel ABPP and MS-based chemical proteomics revealed that the selected BCB amide had a higher target selectivity for BTK in human cells than did an acrylamide probe. Further proteomic study revealed that BTK probes bearing different classes of warhead showed distinct off-target profiles.

Free Research Field

創薬化学

Academic Significance and Societal Importance of the Research Achievements

コバレントドラッグの利点を活かしつつ毒性のリスクを避けるためには、高い標的タンパク質選択性の確保が必要不可欠である。本研究では、既存のシステイン指向反応基とは構造的に大きく異なるビシクロブタンアミドがコバレントドラッグに応用可能であることを示し、反応基のレパートリー拡大に成功した。また、反応基ごとにタンパク質の「好み」があるという点は、今後のコバレントドラッグ創薬においても重要な知見である。