UV Raman Markers for Structural Analysis of Aromatic Side Chains in Proteins

Takeuchi, Hideo

doi:10.2116/analsci.27.1077

Cited by 59 publications

(63 citation statements)

References 58 publications

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“…These bands are indicative of ionized Tyr. 39−42 However, not all mutants that possess Tyr17 show ionization at low temperature. The spectra of mutant W130, in multiple sample preparations at 77 K, showed both ionized and neutral Tyr17.…”

Section: Resultsmentioning

confidence: 99%

Probing Tertiary Structure of Proteins Using Single Trp Mutations with Circular Dichroism at Low Temperature

2014

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Trp is the most spectroscopically informative aromatic amino acid of proteins. However, the near-UV CD spectrum of Trp is complicated because the intensity and sign of 1La and 1Lb bands vary independently. To resolve vibronic structure and gain site-specific information from complex spectra, deconvolution was combined with cooling and site-directed tryptophan substitution. Low temperature near-UV CD was used to probe the local tertiary structure of a loop and α-helix in tear lipocalin. Upon cooling, the enhancement of the intensities of the near-UV CD was not uniform, but depends on the position of Trp in the protein structure. The most enhanced 1Lb band was observed for Trp at position 124 in the α-helix segment matching the known increased conformational mobility during ligand binding. Some aspects of the CD spectra of W28 and W130 were successfully linked to specific rotamers of Trp previously obtained from fluorescence lifetime measurements. The discussion was based on a framework that the magnitude of the energy differences in local conformations governs the changes in the CD intensities at low temperature. The Trp CD spectral classification of Strickland was modified to facilitate the recognition of pseudo-peaks. Near-UV CD spectra harbor abundant information about the conformation of proteins that site directed Trp CD can report.

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Section: Resultsmentioning

confidence: 99%

Probing Tertiary Structure of Proteins Using Single Trp Mutations with Circular Dichroism at Low Temperature

2014

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“…UVRR frequencies and intensities are sensitive to environment, so it is relatively straightforward to correlate UVRR peaks with the local environment of tryptophan and tyrosine residues in proteins, including interactions with metals and charged residues. 80,88,106–111 One advantage of UVRR over electronic tools, such as fluorescence, is that the effects of hydrogen bonding and local dielectric on UVRR peaks are separable, thereby allowing independent investigations of changes in H-bonding or hydrophobicity. 81 Histidine protonation states are easily determined by UVRR studies of protein in D 2 O buffer, and such experiments have been performed on superoxide dismutase and galectins.…”

Section: Ultraviolet Resonance Raman (Uvrr) Spectroscopymentioning

confidence: 99%

Insights into Protein Structure and Dynamics by Ultraviolet and Visible Resonance Raman Spectroscopy

et al. 2015

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Raman spectroscopy is a form of vibrational spectroscopy based on inelastic scattering of light. In resonance Raman spectroscopy, the wavelength of the incident light falls within an absorption band of a chromophore, and this overlap of excitation and absorption energy greatly enhances the Raman scattering efficiency of the absorbing species. The ability to probe vibrational spectra of select chromophores within a complex mixture of molecules makes resonance Raman spectroscopy an excellent tool for studies of biomolecules. In this Current Topic, we discuss the type of molecular insights obtained from steady-state and time-resolved resonance Raman studies of a prototypical photoactive protein, rhodopsin. We also review recent efforts in ultraviolet resonance Raman investigations of soluble and membrane-associated biomolecules, including integral membrane proteins and antimicrobial peptides. These examples illustrate that resonance Raman is a sensitive, selective, and practical method for studying the structures of biological molecules, and the molecular bonding, geometry, and environments of protein cofactors, the backbone, and side chains.

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“…3e) confirms the deprotonation of the side chain of Tyr. Indeed, upon ionization both L a and L b bands of Tyr, which have maxima at 220 nm and 277 nm, display a red shift of about 20 nm (45–47). In aqueous solutions, the 0-0 and 0+800 cm −1 transitions of L b band of Tyr are observed at 282.6 nm and 276.3 nm, respectively (41).…”

Section: Discussionmentioning

confidence: 99%

Cation-π Interactions in Lipocalins: Structural and Functional Implications

2012

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The cation-π interaction impacts protein folding, structural stability, specificity, and molecular recognition. Cation-π interactions have been overlooked in the lipocalin family. To fill this gap, these interactions were analyzed in the 113 crystal and solution structures from the lipocalin family. The cation-π interactions link previously identified structurally conserved regions and reveal new motifs, which are beyond the reach of a sequence alignment algorithm. Functional and structural significance of the interactions were tested experimentally in human tear lipocalin (TL). TL, a prominent and promiscuous lipocalin, has a key role in lipid binding at the ocular surface. Ligand binding modulation through the loop AB at the “open” end the barrel has been erroneously attributed solely to electrostatic interactions. Data revealed that the interloop cation-π interaction in the pair Phe28-Lys108 contributes significantly to stabilize the holo-conformation of the loop AB. Numerous energetically significant and conserved cation-π interactions were uncovered in TL and throughout the lipocalin family. Cation-π interactions, such as the highly conserved Trp17-Arg118 pair in TL, were educed in low temperature experiments of mutants with Trp to Tyr substitutions.

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UV Raman Markers for Structural Analysis of Aromatic Side Chains in Proteins

Cited by 59 publications

References 58 publications

Probing Tertiary Structure of Proteins Using Single Trp Mutations with Circular Dichroism at Low Temperature

Probing Tertiary Structure of Proteins Using Single Trp Mutations with Circular Dichroism at Low Temperature

Insights into Protein Structure and Dynamics by Ultraviolet and Visible Resonance Raman Spectroscopy

Cation-π Interactions in Lipocalins: Structural and Functional Implications

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