Accurate Measurement of Methyl 13C Chemical Shifts by Solid-State NMR for the Determination of Protein Side Chain Conformation: The Influenza A M2 Transmembrane Peptide as an Example Hong, Mei Mishanina, Tatiana Cady, Sarah Cady, Sarah
dc.contributor.department Chemistry 2019-09-20T01:59:49.000 2020-06-30T01:17:01Z 2020-06-30T01:17:01Z Thu Jan 01 00:00:00 UTC 2009 2009-05-14
dc.description.abstract <p>The use of side chain methyl 13C chemical shifts for the determination of the rotameric conformation of Val and Leu residues in proteins by solid-state NMR spectroscopy is described. Examination of the solution NMR stereospecifically assigned methyl groups shows significant correlation between the difference in the two methyl carbons’ chemical shifts and the side chain conformation. It is found that α-helical and β-sheet backbones cause different side chain methyl chemical shift trends. In α-helical Leu’s, a relatively large absolute methyl 13C shift difference of 2.89 ppm is found for the most populated mt rotamer (χ1 = −60°, χ2 = 180°), while a much smaller value of 0.73 ppm is found for the next populated tp rotamer (χ1 = 180°, χ2 = 60°). For α-helical Val residues, the dominant t rotamer (χ1 = 180°) has more downfield Cγ2 chemical shifts than Cγ1 by 1.71 ppm, while the next populated m rotamer (χ1 = −60°) shows the opposite trend of more downfield Cγ1 chemical shift by 1.23 ppm. These significantly different methyl 13C chemical shifts exist despite the likelihood of partial rotameric averaging at ambient temperature. We show that these conformation-dependent methyl 13C chemical shifts can be utilized for side chain structure determination once the methyl 13C resonances are accurately measured by double-quantum (DQ) filtered 2D correlation experiments, most notably the dipolar DQ to single-quantum (SQ) correlation technique. The advantage of the DQ−SQ correlation experiment over simple 2D SQ−SQ correlation experiments is demonstrated on the transmembrane peptide of the influenza A M2 proton channel. The methyl chemical shifts led to predictions of the side chain rotameric states for several Val and Leu residues in this tetrameric helical bundle. The predicted Val rotamers were further verified by dipolar correlation experiments that directly measure the χ1 torsion angles. It was found that the chemical-shift-predicted side chain conformations are fully consistent with the direct torsion angle results; moreover, the methyl 13C chemical shifts are sensitive to ∼5° changes in the χ1 torsion angle due to drug binding.</p>
dc.description.comments <p>This document is the Accepted Manuscript version of a Published Work that appeared in final form in <em>Journal of the American Chemical Society</em>, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see <a href="" target="_blank">10.1021/ja901550q</a>. Posted with permission.</p>
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dc.identifier archive/
dc.identifier.articleid 2154
dc.identifier.contextkey 15358880
dc.identifier.s3bucket isulib-bepress-aws-west
dc.identifier.submissionpath chem_pubs/1151
dc.language.iso en
dc.source.bitstream archive/|||Fri Jan 14 18:52:08 UTC 2022
dc.source.uri 10.1021/ja901550q
dc.subject.disciplines Biochemical and Biomolecular Engineering
dc.subject.disciplines Membrane Science
dc.title Accurate Measurement of Methyl 13C Chemical Shifts by Solid-State NMR for the Determination of Protein Side Chain Conformation: The Influenza A M2 Transmembrane Peptide as an Example
dc.type article
dc.type.genre article
dspace.entity.type Publication
relation.isAuthorOfPublication bdd61196-0f0a-4ec2-9723-b7edddf99843
relation.isOrgUnitOfPublication 42864f6e-7a3d-4be3-8b5a-0ae3c3830a11
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