Conformational Preferences in the Transition States and Tetrahedral Intermediates of Transacylations. Relationships to Enzyme-Bound Conformations of Phosphonate Inhibitors of Lipases and Esterases

2004 ◽  
Vol 108 (52) ◽  
pp. 11740-11751 ◽  
Author(s):  
Yu Takano ◽  
K. N. Houk
Keyword(s):  
Transition States ◽  
Conformational Preferences ◽  
Tetrahedral Intermediates

scholarly journals Assessing the effective factors affecting the conformational preferences and the early and late transition states of the unimolecular retro-ene decomposition reactions of ethyl cyanate, ethyl thiocyanate and ethyl selenocyanate

RSC Advances ◽  
2017 ◽  
Vol 7 (37) ◽  
pp. 22757-22770 ◽  
Author(s):  
Hooshang Atabaki ◽  
Davood Nori-Shargh ◽  
Mohamad Momen-Heravi
Keyword(s):  
Transition States ◽  
Factors Affecting ◽  
Effective Factors ◽  
Decomposition Reactions ◽  
Barrier Heights ◽  
Conformational Preferences ◽  
Late Transition

The variations of Δ[(HCGAE(X3–C4weakening) – HCGAE(X3–C4strengthening)] parameters correlate well with the variations of the retro-ene decomposition reactions barrier heights going from compound1to compound3.

A molecular mechanics study of conformational isomerism in 1- and 3-aryl hydantoins and 3-aryl-2-thiohydantoins

1991 ◽  
Vol 69 (12) ◽  
pp. 1957-1963 ◽  
Author(s):  
Lawrence D. Colebrook
Keyword(s):  
Force Field ◽  
Key Words ◽  
Molecular Mechanics ◽  
Internal Rotation ◽  
Transition States ◽  
Rotational Energy ◽  
Conformational Isomerism ◽  
Hindered Rotation ◽  
Energy Profiles ◽  
Conformational Preferences

Energy profiles for internal rotation about the C—N pivot bond in a series of 1- and 3-aryl hydantoins and 3-aryl-2-thiohydantoins have been computed using the MMX molecular mechanics force field. Rotational ground and transition states have been identified and their energies calculated. Conformational preferences of diastereomeric rotamers have been investigated. Computed rotational energy barriers generally are within ± 2 kcal/mol of the experimentally determined values. Key words: conformational isomerism, hindered rotation, hydantoins, thiohydantoins, molecular mechanics.

NMR spectroscopy in the conformational analysis of peptides: an overview

2020 ◽  
Vol 27 ◽  
Author(s):  
Marian Vincenzi ◽  
Flavia Anna Mercurio ◽  
Marilisa Leone
Keyword(s):  
Nmr Spectroscopy ◽  
Protein Interactions ◽  
3D Structure ◽  
Theoretical Background ◽  
Triple Resonance ◽  
Protein Protein Interactions ◽  
Nmr Studies ◽  
Conformational Preferences ◽  
Dynamic Perspective ◽  
Nmr Methods

Background: NMR spectroscopy is one of the most powerful tools to study the structure and interaction properties of peptides and proteins from a dynamic perspective. Knowing the bioactive conformations of peptides is crucial in the drug discovery field to design more efficient analogue ligands and inhibitors of protein-protein interactions targeting therapeutically relevant systems. Objective: This review provides a toolkit to investigate peptide conformational properties by NMR. Methods: Articles cited herein, related to NMR studies of peptides and proteins were mainly searched through Pubmed and the web. More recent and old books on NMR spectroscopy written by eminent scientists in the field were consulted as well. Results: The review is mainly focused on NMR tools to gain the 3D structure of small unlabeled peptides. It is more application-oriented as it is beyond its goal to deliver a profound theoretical background. However, the basic principles of 2D homonuclear and heteronuclear experiments are briefly described. Protocols to obtain isotopically labeled peptides and principal triple resonance experiments needed to study them, are discussed as well. Conclusion: NMR is a leading technique in the study of conformational preferences of small flexible peptides whose structure can be often only described by an ensemble of conformations. Although NMR studies of peptides can be easily and fast performed by canonical protocols established a few decades ago, more recently we have assisted to tremendous improvements of NMR spectroscopy to investigate instead large systems and overcome its molecular weight limit.

Conformational Preferences of Chiral Acyclic Homooligomeric β2,2-Peptides

2014 ◽  
Vol 14 (10) ◽  
pp. 1225-1234 ◽  
Author(s):  
Fernando Rodriguez ◽  
Francisco Corzana ◽  
Alberto Avenoza ◽  
Jesus Busto ◽  
Jesus Peregrina ◽  
...  
Keyword(s):  
Conformational Preferences
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