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A 13C labeling strategy reveals a range of aromatic side chain motion in calmodulin.

ABSTRACT: NMR relaxation experiments often require site-specific isotopic enrichment schemes in order to allow for quantitative interpretation. Here we describe a new labeling scheme for site-specific (13)C-(1)H enrichment of a single ortho position of aromatic amino acid side chains in an otherwise perdeuterated background by employing a combination of [4-(13)C]erythrose and deuterated pyruvate during growth on deuterium oxide. This labeling scheme largely eliminates undesired contributions to (13)C relaxation and greatly simplifies the fitting of relaxation data using the Lipari-Szabo model-free formalism. This approach is illustrated with calcium-saturated vertebrate calmodulin and oxidized flavodoxin from Cyanobacterium anabaena . Analysis of (13)C relaxation in the aromatic groups of calcium-saturated calmodulin indicates a wide range of motion in the subnanosecond time regime.

SUBMITTER: Kasinath V

PROVIDER: S-EPMC3726223 | biostudies-literature | 2013 Jul

REPOSITORIES: biostudies-literature

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A 13C labeling strategy reveals a range of aromatic side chain motion in calmodulin.

Kasinath Vignesh V Valentine Kathleen G KG Wand A Joshua AJ

Journal of the American Chemical Society 20130619 26

NMR relaxation experiments often require site-specific isotopic enrichment schemes in order to allow for quantitative interpretation. Here we describe a new labeling scheme for site-specific (13)C-(1)H enrichment of a single ortho position of aromatic amino acid side chains in an otherwise perdeuterated background by employing a combination of [4-(13)C]erythrose and deuterated pyruvate during growth on deuterium oxide. This labeling scheme largely eliminates undesired contributions to (13)C rela ...[more]

PMID: 23767407

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