Chemical post-translational
methods allow convergent side-chain
editing of proteins without needing to resort to genetic intervention.
Current approaches that allow the creation of constitutionally native
side chains via C–C bond formation, using off-protein carbon-centered
C· radicals added to unnatural amino acid radical acceptor (SOMOphile,
singly occupied molecular orbital (SOMO)) “tags” such
as dehydroalanine, are benign and wide-ranging. However, they also
typically create epimeric mixtures of d
/l-residues.
Here, we describe a light-mediated desulfurative method that, through
the creation and reaction of stereoretained on-protein
l-alanyl Cβ· radicals, allows Cβ–Hγ, Cβ–Oγ, Cβ–Seγ, Cβ–Bγ, and Cβ–Cγ bond formation to flexibly generate site-selectively
edited proteins with full retention of native stereochemistry under
mild conditions from a natural amino acid precursor. This methodology
shows great potential to explore protein side-chain diversity and
function and in the construction of useful bioconjugates.
We describe an instrument configuration based on the
Orbitrap Exploris
480 mass spectrometer that has been coupled to an Omnitrap platform.
The Omnitrap possesses three distinct ion-activation regions that
can be used to perform resonant-based collision-induced dissociation,
several forms of electron-associated fragmentation, and ultraviolet
photodissociation. Each section can also be combined with infrared
multiphoton dissociation. In this work, we demonstrate all these modes
of operation in a range of peptides and proteins. The results show
that this instrument configuration produces similar data to previous
implementations of each activation technique and at similar efficiency
levels. We demonstrate that this unique instrument configuration is
extremely versatile for the investigation of polypeptides.
We describe an instrument configuration based on the Orbitrap Exploris 480 mass spectrometer that has been coupled to an Omnitrap platform. The Omnitrap possesses three distinct ion-activation regions, that can be used to perform resonant based collision induced dissociation, several forms of electron associated fragmentation, and ultraviolet photodissociation. Each section can also be combined with infrared multiphoton dissociation. In this work, we demonstrate all these modes of operation on a range of peptides and proteins. The results show that this instrument configuration produces similar data to previous implementations of each activation technique and at similar efficiency levels. We demonstrate that this unique instrument configuration is extremely versatile for the interrogation of polypeptides.
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