scholarly journals Resolving voltage-dependent structural changes of a membrane photoreceptor by surface-enhanced IR difference spectroscopy

2008 ◽  
Vol 105 (34) ◽  
pp. 12113-12117 ◽  
Author(s):  
X. Jiang ◽  
E. Zaitseva ◽  
M. Schmidt ◽  
F. Siebert ◽  
M. Engelhard ◽  
...  
Keyword(s):  
Structural Changes ◽  
Difference Spectroscopy ◽  
Surface Enhanced ◽  
Voltage Dependent

Raman and Surface Enhanced Raman Spectroscopy of Titanium Carboxylates

1992 ◽  
Vol 271 ◽  
Author(s):  
Beatrice A. Van Vlierberge-Torgerson ◽  
Dilum Dunuwila ◽  
Kris A. Berglund
Keyword(s):  
Raman Spectroscopy ◽  
Structural Changes ◽  
Titanium Isopropoxide ◽  
Surface Enhanced Raman Spectroscopy ◽  
Organic Films ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Metal Organic ◽  
The Relationship ◽  
Hydrolysis Of

ABSTRACTPorous stable metal-organic films can be processed under mild conditions by the hydrolysis of carboxylic acid and titanium isopropoxide mixtures. It is of importance to establish the structure of such materials. Raman spectroscopy is a useful technique in determining structural changes in titanium isopropoxide carboxylate solutions, but weak scattering does not allow for study of thin films unless surface enhancement is used. In an attempt to elucidate the relationship between coating solutions and the final structure of a cast film, we discuss Raman spectra of precursor solutions in a variety of conditions.

Effect Of pH On The Stability And Conformation Of α-Thrombin

1981 ◽  
Author(s):  
German B Villanueva
Keyword(s):  
Chemical Modification ◽  
Structural Changes ◽  
Low Ph ◽  
Tryptophan Residue ◽  
Difference Spectroscopy ◽  
Compact Structure ◽  
Tyrosine Residues ◽  
Charge Interaction ◽  
The Stability ◽  
Peptide Region

It is known that storage at pH 6 stabilizes thrombin against inactivation. In order to determine whether structural changes accompany this stabilization, the conformation of human α-thrombin at pH 6.0 and 7.5 was investigated by chemical modification, solvent perturbation, UV difference spectroscopy and circular dichroism. It was shown that the CD spectra of α-thrombin at 230-200 nm peptide region were indistinguishable at two pH values indicating no difference in the secondary structure. However, differences were observed in the 320-250 nm aromatic region suggesting some changes in the microenvironment of the aromatic chromophores. Solvent perturbation in 20% ethylene glycol indicated 3.7 ± 0.5 Trp and 7.8 ± 0.5 Tyr were exposed to the solvent at pH 6.0 while 4.3 ± 0.4 Trp and 8.4 ± 0.5 Tyr were exposed at pH 7.5. Chemical modification of tryptophan residue by dimethyl(2-hydroxy- 5-nitrobenzyl)sulfonium bromide in a 100-fold molar excess of the reagent showed 3 reactive residues at pH 6.0 and 6 at pH 7.5. These results suggest that when thrombin is exposed to low pH, structural changes occur that decrease the relative degree of exposure of tryptophan and tyrosine residues. Furthermore, UV difference spectroscopy showed the development of a positive differential spectrum when thrombin at pH 6.0 was exposed to pH 7.5. From this study, it is concluded that the stability of thrombin at pH 6.0 is due to a more compact structure of the enzyme which is probably a result of reduced charge interaction at low pH.

Light-induced structural changes during early photo-intermediates of the eubacterial Cl−pump Fulvimarina rhodopsin observed by FTIR difference spectroscopy

RSC Advances ◽  
2016 ◽  
Vol 6 (1) ◽  
pp. 383-392 ◽  
Author(s):  
Faisal Hammad Mekky Koua ◽  
Hideki Kandori
Keyword(s):  
Marine Bacteria ◽  
Structural Changes ◽  
Difference Spectroscopy ◽  
Ftir Difference Spectroscopy

Fulvimarina pelagirhodopsin (FR) is a member of inward eubacterial light-activated Cl−translocating rhodopsins (ClR) that were found recently in marine bacteria.

scholarly journals Myotonia-related mutations in the distal C-terminus of ClC-1 and ClC-0 chloride channels affect the structure of a poly-proline helix

2007 ◽  
Vol 403 (1) ◽  
pp. 79-87 ◽  
Author(s):  
María J. Macías ◽  
Oscar Teijido ◽  
Giovanni Zifarelli ◽  
Pau Martin ◽  
Ximena Ramirez-Espain ◽  
...  
Keyword(s):  
Chloride Channels ◽  
Structural Changes ◽  
Surface Expression ◽  
Muscle Fibres ◽  
Coding Region ◽  
Protein Coding ◽  
C Terminus ◽  
Voltage Dependent ◽  
Common Gate ◽  
Spectroscopy Studies

Myotonia is a state of hyperexcitability of skeletal-muscle fibres. Mutations in the ClC-1 Cl− channel cause recessive and dominant forms of this disease. Mutations have been described throughout the protein-coding region, including three sequence variations (A885P, R894X and P932L) in a distal C-terminal stretch of residues [CTD (C-terminal domain) region] that are not conserved between CLC proteins. We show that surface expression of these mutants is reduced in Xenopus oocytes compared with wild-type ClC-1. Functional, biochemical and NMR spectroscopy studies revealed that the CTD region encompasses a segment conserved in most voltage-dependent CLC channels that folds with a secondary structure containing a short type II poly-proline helix. We found that the myotonia-causing mutation A885P disturbs this structure by extending the poly-proline helix. We hypothesize that this structural modification results in the observed alteration of the common gate that acts on both pores of the channel. We provide the first experimental investigation of structural changes resulting from myotonia-causing mutations.

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