Formation of Ring A in the Biosynthesis of Hopanoids from Squalene. A Density Functional Study

2004 ◽  
Vol 69 (1) ◽  
pp. 261-266 ◽  
Author(s):  
B. Andes Hess
Keyword(s):  
Activation Energy ◽  
Density Functional Calculations ◽  
Density Functional ◽  
Ring Closure ◽  
Functional Study ◽  
Chair Conformer ◽  
Density Functional Study ◽  
Concerted Reaction

Density functional calculations were carried out on the ring closure of the 2,6-dimethyloct-6-en-2-yl cation to a chair conformer of the 1,2,3,3-tetramethylcyclohexyl cation as a model for the first step in the biosynthetic cyclization of squalene to the triterpene hopanoids. The concerted reaction was found to have an activation energy of 4.6 kcal/mol and to be exothermic by 11.5 kcal/mol.

Energetics of native defects in anatase TiO2: a hybrid density functional study

2016 ◽  
Vol 18 (43) ◽  
pp. 30040-30046 ◽  
Author(s):  
Adisak Boonchun ◽  
Pakpoom Reunchan ◽  
Naoto Umezawa
Keyword(s):  
Electronic Structures ◽  
Density Functional Calculations ◽  
Density Functional ◽  
Anatase Tio2 ◽  
Functional Study ◽  
Native Defects ◽  
Density Functional Study ◽  
Hybrid Density Functional

The energetics and electronic structures of native defects in anatase TiO2 are comprehensively studied using hybrid density functional calculations.

scholarly journals A Density-Functional Study of the Conformational Preference of Acetylcholine in the Neutral Hydrolysis

Molecules ◽  
2020 ◽  
Vol 25 (3) ◽  
pp. 670 ◽  
Author(s):  
Rizka N. Fadilla ◽  
Febdian Rusydi ◽  
Nufida D. Aisyah ◽  
Vera Khoirunisa ◽  
Hermawan K. Dipojono ◽  
...  
Keyword(s):  
Transition State ◽  
Density Functional Calculations ◽  
Density Functional ◽  
Experimental Results ◽  
Functional Study ◽  
Conformational Preference ◽  
Reaction Energy ◽  
Density Functional Study ◽  
One Step ◽  
Experimental Findings

Acetylcholine, which is associated with Alzheimer’s disease, is widely known to have conformers. The preference of each conformer to undergo neutral hydrolysis is yet to be considered. In this study, we employed density-functional calculations to build the conformers and investigated their preference in one-step neutral hydrolysis. The results showed the preference in ten possible hydrolysis pathways involving seven acetylcholine conformers (reactant), four transition state structures, and two choline conformers (product). Three out of the seven acetylcholine conformers predicted from the results confirmed experimental findings on the conformers stability. We suggested that two out of ten possible pathways were observed in the experimental results based on agreement in reaction energy. Eventually, this study will emphasize the importance of considering acetylcholine conformers in its hydrolysis study.

scholarly journals A broken-symmetry density functional study of structures, energies, and protonation states along the catalytic O–O bond cleavage pathway in ba3 cytochrome c oxidase from Thermus thermophilus

2016 ◽  
Vol 18 (31) ◽  
pp. 21162-21171 ◽  
Author(s):  
Wen-Ge Han Du ◽  
Andreas W. Götz ◽  
Longhua Yang ◽  
Ross C. Walker ◽  
Louis Noodleman
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Density Functional Calculations ◽  
Density Functional ◽  
Bond Cleavage ◽  
Thermus Thermophilus ◽  
Broken Symmetry ◽  
Functional Study ◽  
Density Functional Study

The [Fea3, CuB] dinuclear center states along the O–O bond cleavage pathway in ba3 cytochrome c oxidase have been studied using broken-symmetry density functional calculations.

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