Molecular mechanics calculations of cyclosporin A analogs. Effect of chirality and degree of substitution on the side-chain conformations of (2S,3R,4R,6E)-3-hydroxy-4-methyl-2-(methylamino)-6-octenoic acid and related derivatives

1989 ◽  
Vol 111 (22) ◽  
pp. 8351-8362 ◽  
Author(s):  
Kristine E. Miller ◽  
Daniel H. Rich
Keyword(s):  
Cyclosporin A ◽  
Molecular Mechanics ◽  
Degree Of Substitution ◽  
Side Chain ◽  
Molecular Mechanics Calculations ◽  
Chain Conformations

Molecular Mechanics Investigation on Side-Chain Conformations of a 17α-Ethyl-17β-hydroxy Steroid with Regard to Receptor Binding

1987 ◽  
Vol 42 (3) ◽  
pp. 221-224 ◽  
Author(s):  
Martin Bohl
Keyword(s):  
Hydrogen Bonds ◽  
Oxygen Atom ◽  
Molecular Mechanics ◽  
Receptor Protein ◽  
Hydroxyl Group ◽  
Side Chain ◽  
Ring Conformation ◽  
Sterically Hinder ◽  
Chain Conformations ◽  
Hydroxy Steroid

Energetically favourable conformations for simultaneous intramolecular rotations of both the 17 α ethyl side chain and the 17 β hydroxyl group of a model steroid are calculated by MM2 molecular mechanics. In accordance with recent IR and NMR interpretations, the 17α substituent is found to preferably adopt conformations which may sterically hinder the formation of hydrogen bonds between the steroidal 17β oxygen atom and the receptor protein. Furthermore, the 17a ethyl substitution is computed to influence the D-ring conformation and to alter the location of the 17β oxygen function by 28 pm in space.

The conformational properties of calix[4]arenes 1h NMR and molecular mechanics calculations

1989 ◽  
Vol 86 ◽  
pp. 945-954 ◽  
Author(s):  
F. Bayard ◽  
D. Decoret ◽  
D. Pattou ◽  
J. Royer ◽  
A. Satrallah ◽  
...  
Keyword(s):  
Molecular Mechanics ◽  
1H Nmr ◽  
Molecular Mechanics Calculations ◽  
Conformational Properties

Stereospecific Association of C-20 Epimers of 3β-Hydroxy-16-oxo-24-nor-17-azachol-5-eno-23-nitryle

1997 ◽  
Vol 52 (6) ◽  
pp. 749-756
Author(s):  
Zofia Plesnar ◽  
Stanisław Malanowski ◽  
Zenon Lotowski ◽  
Jacek W. Morzycki ◽  
Jadwiga Frelek ◽  
...  
Keyword(s):  
Proton Nuclear Magnetic Resonance ◽  
Side Chain ◽  
Water Molecules ◽  
Carbonyl Groups ◽  
Nmr Data ◽  
Molecular Modelling Studies ◽  
Modelling Studies ◽  
Lactam Carbonyl ◽  
Self Association ◽  
Chain Conformations

Abstract The cryoscopic measurements show that title compounds are strongly associated in CHCl3 solutions. The association of the 20 R epimer is distinctly less pronounced than that of the 20 S epipmer. Self-association of the 20 S epimer leads to the formation of very large com­plexes. The 20 R epimer forms associates via water molecules. The dissimilarity may be ex­plained in terms of different accessibility of the lactam carbonyl groups in the two epimers for the association. It is proposed that the association process is controlled by the configura­tion at the carbon atom C(20) and conformation around the C(20)-C(22) bond. Populations of side chain conformations of both epimers were determined by means of proton nuclear magnetic resonance. It was found for the 20 R epimer that the t and the -g rotamers are almost equally populated, and the rotamer +g is excluded. For the 20 S epimer the +g rotamer predominates over the t one, and the -g rotamer is excluded. The NMR data are fully consistent with the results of the molecular modelling studies.

Molecular Mechanics Calculations and the Metal Ion Selective Extraction of Lanthanoids

1998 ◽  
Vol 37 (13) ◽  
pp. 3310-3315 ◽  
Author(s):  
Peter Comba ◽  
Karsten Gloe ◽  
Katsutoshi Inoue ◽  
Torsten Krüger ◽  
Holger Stephan ◽  
...  
Keyword(s):  
Molecular Mechanics ◽  
Metal Ion ◽  
Selective Extraction ◽  
Molecular Mechanics Calculations
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