• Title/Summary/Keyword: Biophysical

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Transverse relaxation-optimized HCN experiment for tautomeric states of histidine sidechains

  • Schmidt, Holger;Himmel, Sebastian;Walter, Korvin F.A.;Klaukien, Volker;Funk, Michael;Lee, Dong-Han
    • Journal of the Korean Magnetic Resonance Society
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    • v.12 no.2
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    • pp.89-95
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    • 2008
  • Function of protein is frequently related with tautomeric states of histidine sidechains. Thus, several NMR experiments were developed to determine the tautomeric states of histidines. However, poor sensitivity of these experiments caused by long duration of magnetization transfer periods is unavoidable. Here, we alleviate the sensitivity of HCN experiment for determining the tautomeric states of histidine residues using TROSY principle to suppress transverse relaxation of $^{13}C$ spins during long polarization transfer delays involving $^{13}C-^{15}N$ scalar couplings. In addition, this experiment was used to assign the sidechain resonances of histidines. These assignments can be used to follow the pH-titration of histidine sidechains.

Sensitivity Enhancement of Methyl-TROSY by Longitudinal 1H Relaxation Optimization

  • Lee, Dong-Han;Vijayan, Vinesh;Montaville, Pierre;Becker, Stefan;Griesinger, Christian
    • Journal of the Korean Magnetic Resonance Society
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    • v.13 no.1
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    • pp.15-26
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    • 2009
  • The NMR detection of methyl groups is of keen interest because they provide the long-range distance information required to establish global folds of high molecular weight proteins. Using longitudinal $^1H$ relaxation optimization, we achieve a gain in sensitivity of approximately 1.6-fold in the methyl-TROSY and its NOESY experiments for the 38 kDa protein mitogen activated protein kinase p38 in its fully protonated and $^{13}C$ and $^{15}N$ labeled state.

Photochemistry of pharaonis phoborhodopsin and its interaction with the transducer

  • Kamo, Naoki;Shimono, Kazumi;Iwamoto, Masayuki;Sudo, Yuki;Yoshida, Hideaki
    • Journal of Photoscience
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    • v.9 no.2
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    • pp.102-105
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    • 2002
  • Phoborhodopsin (pR or sensory rhodopsin II, sRII; the absorption maximum of ∼ 500 nm) is a retinoid protein and works as a photoreceptor of the negative phototaxis of Halobacterium salinarum. pharaonis phoborhodopsin (ppR or pharaonis sensory rhodopsin II, psRII) is a corresponding protein of Natronobacterium pharaonis. These sensory proteins form a complex with a cognate transducer protein in the membrane, and this complex transmits the light-signal to the cytoplasm to evoke avoidance reaction from blue-green light. Recently, the functional expression in Escherichia coli membrane of ppR was achieved, which can afford a large amount of the protein and enables mutant studies to clarify the role of various amino acid residues. A truncated transducer which can bind to ppR is also expressed in Escherichia. coli membrane. In this article, we will review properties of ppR mainly using observations of our laboratory; which contains photochemistry (photocycle), light-driven proton uptake, release and transport, F -helix titling during photocycle and association of the transducer.

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