Hydrolysis of the 1,4-beta-linkages between N-acetyl-D-glucosamine and N-acetylmuramic acid in peptidoglycan heteropolymers of the prokaryotes cell walls.
Toward Precise Interpretation of DEER-Based Distance Distributions: Insights from Structural Characterization of V1 Spin-Labeled Side Chains.
A.R.Balo,
H.Feyrer,
O.P.Ernst.
ABSTRACT
Pulsed electron paramagnetic resonance experiments can measure individual
distances between two spin-labeled side chains in proteins in the range of
∼1.5-8 nm. However, the flexibility of traditional spin-labeled side chains
leads to diffuse spin density loci and thus distance distributions with
relatively broad peaks, thereby complicating the interpretation of protein
conformational states. Here we analyzed the spin-labeled V1 side chain, which is
internally anchored and hence less flexible. Crystal structures of V1-labeled T4
lysozyme constructs carrying the V1 side chain on α-helical segments suggest
that V1 side chains adopt only a few discrete rotamers. In most cases, only one
rotamer is observed at a given site, explaining the frequently observed narrow
distance distribution for doubly V1-labeled proteins. We used the present data
to derive guidelines that may allow distance interpretation of other V1-labeled
proteins for higher-precision structural modeling.
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