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Free keywords:
Assignment, Deuteration, Ion channel, MAS, Solid-state NMR, Structural constraints
Abstract:
Solid-state Nuclear Magnetic Resonance can
provide detailed insight into structural and dynamical
aspects of complex biomolecules. With increasing molec-
ular size, advanced approaches for spectral simplification
and the detection of medium to long-range contacts
become of critical relevance. We have analyzed the pro-
tonation pattern of a membrane-embedded ion channel that
was obtained from bacterial expression using protonated
precursors and D
2
O medium. We find an overall reduction
of 50% in protein protonation. High levels of deuteration at
H
a
and H
b
positions reduce spectral congestion in
(
1
H,
13
C,
15
N) correlation experiments and generate a
transfer profile in longitudinal mixing schemes that can be
tuned to specific resonance frequencies. At the same time,
residual protons are predominantly found at amino-acid
side-chain positions enhancing the prospects for obtaining
side-chain resonance assignments and for detecting med-
ium to long-range contacts. Fractional deuteration thus
provides a powerful means to aid the structural analysis of
complex biomolecules by solid-state NMR.
