Ultrafast Multidimensional Infrared Spectroscopy of Transient Structures – New Insights into the FeFe[Hydrogenase] Enzyme Reaction Mechanism

2010 ◽  
Author(s):  
G.M. Bonner ◽  
A.I. Stewart ◽  
J.A. Wright ◽  
S. Kaziannis ◽  
S. Santabarbara ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Reaction Mechanism ◽  
Enzyme Reaction ◽  
Transient Structures ◽  
Hydrogenase Enzyme

Determination of the Photolysis Products of [FeFe]Hydrogenase Enzyme Model Systems using Ultrafast Multidimensional Infrared Spectroscopy

2010 ◽  
Vol 49 (20) ◽  
pp. 9563-9573 ◽  
Author(s):  
Andrew I. Stewart ◽  
Joseph A. Wright ◽  
Gregory M. Greetham ◽  
Spiridon Kaziannis ◽  
Stefano Santabarbara ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Model Systems ◽  
Enzyme Model ◽  
Hydrogenase Enzyme

Kinetics and Reaction Mechanism of the Carbamylphosphate Synthetase of a Multienzyme Aggregate from Yeast

1975 ◽  
Vol 53 (6) ◽  
pp. 721-730 ◽  
Author(s):  
David M. Aitken ◽  
Peter F. Lue ◽  
J. Gordin Kaplan
Keyword(s):  
Reaction Mechanism ◽  
Feedback Inhibition ◽  
Enzyme Reaction ◽  
Competitive Inhibitor ◽  
Potassium Ions ◽  
Ammonium Ions ◽  
Nitrogen Donor ◽  
Sequential Addition ◽  
A Site ◽  
Carbamylphosphate Synthetase

We have studied the kinetics and reaction mechanism of the carbamylphosphate synthetase of an enzyme aggregate functioning in the pyrimidine pathway of yeast. Mg–ATP was found to be one of the substrates of the enzyme reaction which was activated by free Mg2+ and inhibited by free ATP. Feedback inhibition by UTP was non-competitive with respect to both glutamine and bicarbonate. Potassium ions were essential for activity and could not be replaced by sodium. Glutamine could be replaced partially by ammonium ions as nitrogen donor. A bicarbonate-dependent cleavage of ATP was shown to take place in the absence of L-glutamine; L-glutamate was a competitive inhibitor of L-glutamine and the enzyme was shown to synthesize ATP when incubated with ADP and carbamyl phosphate. The reaction mechanism was found to involve sequential addition of the substrates bicarbonate and Mg–ATP and release of ADP, followed by addition of the third substrate glutamine. The purine nucleotide XMP had a pronounced activating effect on the enzyme, acting at a site different from that of UTP. Saturating levels of Mg–ATP eliminated this activation.

scholarly journals Dependence of enzyme reaction mechanism on protonation state of titratable residues and QM level description: lactate dehydrogenase

2005 ◽  
pp. 5873 ◽  
Author(s):  
Silvia Ferrer ◽  
Estanislao Silla ◽  
Iñaki Tuñón ◽  
Mónica Oliva ◽  
Vicent Moliner ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Lactate Dehydrogenase ◽  
Enzyme Reaction ◽  
Protonation State

Surface Chemistry of Silicon and Germanium Treated with Hydrofluoric Acid Solutions: Slow Reactions of Process Residuals

1990 ◽  
Vol 204 ◽  
Author(s):  
J. Yota ◽  
V.A. Burrows
Keyword(s):  
Thin Film ◽  
Infrared Spectroscopy ◽  
Reaction Mechanism ◽  
Surface Chemistry ◽  
Hydrofluoric Acid ◽  
Ammonium Fluoride ◽  
Ammonium Salts ◽  
Acid Solutions ◽  
Reactive Intermediate ◽  
Silicon And Germanium

ABSTRACTSolutions of hydrofluoric acid are used extensively in the processing of semiconductors, primarily in etching and in oxide stripping procedures. Such solutions are often buffered with ammonium fluoride to insure constant oxide stripping rates. Infrared spectroscopy of silicon and germanium surfaces treated with such solutions indicates that a thin film of ammonium salts will deposit on the materials unless they are immediately and very thoroughly rinsed following treatment. This thin film, comprised initially of ammonium bifluoride (NH4FHF), reacts with the semiconductor material to form ammonium fluoride (NH4F) as a reactive intermediate, and ammonium hexafluorometallate ((NH4)2 SiF6 or (NH4)2 GeF6). These reactions occur very slowly, over hours or days. They are apparently driven by favorable thermodynamics. This explanation is supported by the absence of comparable reactions using analogous chlorine-based solutions (HCI/NH4 CI). Aspects of the reaction mechanism for hexafluorometallate production is presented.

Sign in / Sign up

Export Citation Format

Share Document