Boron Activated Covalent Modification and Micro-Dissection of Amyloid Deposits in Alzheimer’s Disease Brain Tissue

ABSTRACT: Congo Red (CR) dye is historically used for histochemical staining of amyloid deposition in tissue. Its characteristic aryl azo moiety renders it chemically stable as a non-covalent pan-amyloid binder. Here, we discover in serendipity that the CR dye can covalently modify amyloid proteins by activation of the inert azo bond using neutral borate buffer at ambient temperature. We first show that boronic acid is responsible for azo bond-mediated protein bioconjugation. Furthermore, we also observe that ultraviolet light-induced azo trans-to-cis isomerization significantly enhances the labeling efficiency. Leveraging the discovered covalent chemistry, we apply CR-alkyne derivative with a click enrichment handle to label, capture and enrich amyloid deposits in Alzheimer’s disease (AD) mouse brain tissue. Finally, we identify the composition of amyloid deposits by proteomics profiling, revealing typical neurodegenerative diseases biomarkers, including MAPT and 14-3-3 family proteins. Overall, this work presents a new type of azo based bioconjugation chemistry previously known to be inert but herein activated by neutral borate buffer.

INSTRUMENT(S): timsTOF Pro

ORGANISM(S): Mus Musculus (mouse)

TISSUE(S): Brain

DISEASE(S): Alzheimer's Disease 1

SUBMITTER: Huan Feng  

LAB HEAD: Huan Feng

PROVIDER: PXD062299 | Pride | 2025-03-27

REPOSITORIES: Pride