A tale of two bioconjugations: pH controlled divergent reactivity of protein a-oxo aldehydes in competing a-oxo-Mannich and catalyst-free aldol ligations

TY - JOUR

T1 - A tale of two bioconjugations

T2 - pH controlled divergent reactivity of protein a-oxo aldehydes in competing a-oxo-Mannich and catalyst-free aldol ligations

AU - Keenan, Tessa

AU - Spears, Richard J

AU - Akkad, Saeed

AU - Mahon, Clare S

AU - Hatton, Natasha E

AU - Walton, Julia

AU - Noble, Amanda

AU - Yates, Nicholas D

AU - Baumann, Christoph G

AU - Parkin, Alison

AU - Signoret, Nathalie

AU - Fascione, Martin A

N1 - © 2021 American Chemical Society. This is an author-produced version of the published paper. Uploaded in accordance with the publisher’s self-archiving policy. Further copying may not be permitted; contact the publisher for details

PY - 2021/11/19

Y1 - 2021/11/19

N2 - Site-selective chemical methods for protein bioconjugation have revolutionised the fields of cell and chemical biology through the development of novel protein/enzyme probes bearing fluorescent, spectroscopic or even toxic cargos. Herein we report two new methods for the bioconjugation of a-oxo aldehyde handles within proteins using small molecule aniline and/or phenol probes. The ‘a-oxo-Mannich’ and ‘catalyst-free aldol’ ligations both compete for the electrophilic a-oxo aldehyde which displays pH divergent reactivity proceeding through the “Mannich” pathway at acidic pH to afford bifunctionalised bioconjugates, and the “catalyst-free aldol” pathway at neutral pH to afford monofunctionalised bioconjugates. We explore the substrate scope and utility of both these bioconjugations in the construction of neoglycoproteins, in the process formulating a mechanistic rationale for how both pathways intersect with each other at different reaction pH.

AB - Site-selective chemical methods for protein bioconjugation have revolutionised the fields of cell and chemical biology through the development of novel protein/enzyme probes bearing fluorescent, spectroscopic or even toxic cargos. Herein we report two new methods for the bioconjugation of a-oxo aldehyde handles within proteins using small molecule aniline and/or phenol probes. The ‘a-oxo-Mannich’ and ‘catalyst-free aldol’ ligations both compete for the electrophilic a-oxo aldehyde which displays pH divergent reactivity proceeding through the “Mannich” pathway at acidic pH to afford bifunctionalised bioconjugates, and the “catalyst-free aldol” pathway at neutral pH to afford monofunctionalised bioconjugates. We explore the substrate scope and utility of both these bioconjugations in the construction of neoglycoproteins, in the process formulating a mechanistic rationale for how both pathways intersect with each other at different reaction pH.

KW - Aldehydes/chemistry

KW - Aniline Compounds/chemistry

KW - Catalysis

KW - Hydrogen-Ion Concentration

KW - Mannich Bases/chemistry

KW - Peptides/chemistry

KW - Proteins/chemistry

U2 - 10.1021/acschembio.1c00531

DO - 10.1021/acschembio.1c00531

M3 - Article

C2 - 34751550

SN - 1554-8929

VL - 16

SP - 2387

EP - 2400

JO - ACS Chemical Biology

JF - ACS Chemical Biology

IS - 11

ER -