Vibrational Echo Chemical Exchange Spectroscopy

2013 ◽  
pp. 1-34 ◽  
Author(s):  
Michael Fayer
Keyword(s):  
Chemical Exchange ◽  
Exchange Spectroscopy ◽  
Vibrational Echo

scholarly journals Ion-water hydrogen-bond switching observed with 2D IR vibrational echo chemical exchange spectroscopy

2008 ◽  
Vol 106 (2) ◽  
pp. 375-380 ◽  
Author(s):  
D. E. Moilanen ◽  
D. Wong ◽  
D. E. Rosenfeld ◽  
E. E. Fenn ◽  
M. D. Fayer
Keyword(s):  
Hydrogen Bond ◽  
Chemical Exchange ◽  
2D Ir ◽  
Exchange Spectroscopy ◽  
Vibrational Echo ◽  
Water Hydrogen

scholarly journals Discovery and characterization of a sulfoquinovose mutarotase using kinetic analysis at equilibrium by exchange spectroscopy

2018 ◽  
Vol 475 (7) ◽  
pp. 1371-1383 ◽  
Author(s):  
Palika Abayakoon ◽  
James P. Lingford ◽  
Yi Jin ◽  
Christopher Bengt ◽  
Gideon J. Davies ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Active Sites ◽  
Glucuronic Acid ◽  
Chemical Exchange ◽  
Sequence Analyses ◽  
Uncharacterized Gene ◽  
Exchange Spectroscopy ◽  
First Time ◽  
Better Than

Bacterial sulfoglycolytic pathways catabolize sulfoquinovose (SQ), or glycosides thereof, to generate a three-carbon metabolite for primary cellular metabolism and a three-carbon sulfonate that is expelled from the cell. Sulfoglycolytic operons encoding an Embden–Meyerhof–Parnas-like or Entner–Doudoroff (ED)-like pathway harbor an uncharacterized gene (yihR in Escherichia coli; PpSQ1_00415 in Pseudomonas putida) that is up-regulated in the presence of SQ, has been annotated as an aldose-1-epimerase and which may encode an SQ mutarotase. Our sequence analyses and structural modeling confirmed that these proteins possess mutarotase-like active sites with conserved catalytic residues. We overexpressed the homolog from the sulfo-ED operon of Herbaspirillum seropedicaea (HsSQM) and used it to demonstrate SQ mutarotase activity for the first time. This was accomplished using nuclear magnetic resonance exchange spectroscopy, a method that allows the chemical exchange of magnetization between the two SQ anomers at equilibrium. HsSQM also catalyzed the mutarotation of various aldohexoses with an equatorial 2-hydroxy group, including d-galactose, d-glucose, d-glucose-6-phosphate (Glc-6-P), and d-glucuronic acid, but not d-mannose. HsSQM displayed only 5-fold selectivity in terms of efficiency (kcat/KM) for SQ versus the glycolysis intermediate Glc-6-P; however, its proficiency [kuncat/(kcat/KM)] for SQ was 17 000-fold better than for Glc-6-P, revealing that HsSQM preferentially stabilizes the SQ transition state.

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