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.

Modeling of the Adsorption Mechanisms and Selectivity of the Molecular Imprinted Particles for Norfloxacin

2014 ◽  
Vol 1030-1032 ◽  
pp. 121-124
Author(s):  
Song Li ◽  
Lei Fang
Keyword(s):  
Hydrogen Bonds ◽  
Oxygen Atom ◽  
Bisphenol A ◽  
Computational Chemistry ◽  
Molecular Mechanics ◽  
Binding Sites ◽  
Molecular Conformation ◽  
The Other ◽  
Hydroxyl Group ◽  
Adsorption Mechanisms

Molecular conformation and binding modeling were built by Hyperchem 8.0 computational chemistry package and the optimum molecular conformation was obtained by molecular mechanics optimizer. It was found that there were two types of binding sites for norfloxacin on the molecular imprinted particles (MIPs).One was the hydrogen bonds between oxygen atom of MIPs with the carbonyl group of norfloxacin and the other one was the hydrogen bonds between oxygen atom of MIPs with the hydroxyl group of norfloxacin. Moreover, the energies change of the molecules were1.69 x106 J/mol,1.80x106 J/mol and 5.37x106 J/mol and 2.54 x106 J/mol during the binding process of the norfloxacin (NOR), ciprofloxacin (CIP), bisphenol A (BPA) and tonalide (TON) onto the MIPs, respectively. The result indicated that the MIPs had a good selectivity for NOR and CIP than BPA and TON.

scholarly journals The specificity of a 7 α-hydroxy steroid dehydrogenase from Escherichia coli

1976 ◽  
Vol 157 (1) ◽  
pp. 207-210 ◽  
Author(s):  
E S Haslewood ◽  
G A D Haslewood
Keyword(s):  
Escherichia Coli ◽  
Crude Enzyme ◽  
Hydroxyl Group ◽  
Side Chain ◽  
Improved Method ◽  
Hydroxy Steroid ◽  
Steroid Dehydrogenase

1. Thirty-eight steroids were tested as substrates for a 7 alpha-hydroxy steroid dehydrogenase preparation from a strain of Escherichia coli; an improved method of making the crude enzyme is described. 2. Steroids having a 7 alpha-hydroxyl group in the molecule were substrates except (a) when the 5 beta-cholan-24-oic acid side chain was shortened to less than four carbon atoms and (b) in certain cases when sulphate ester groups were present in the molecule. 3. For testing with the enzyme, a new specimen of 7 alpha-hydroxy-3,12-dioxo-5 beta-cholan-24-oic acid was made, which had properties different from those previously described.

scholarly journals Crystal structure and Hirshfeld surface analysis of the methanol solvate of sclareol, a labdane-type diterpenoid

2020 ◽  
Vol 76 (3) ◽  
pp. 294-297
Author(s):  
Memoona Bibi ◽  
M. Iqbal Choudhary ◽  
Sammer Yousuf
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Surface Analysis ◽  
Title Compound ◽  
Hirshfeld Surface ◽  
Hirshfeld Surface Analysis ◽  
Hydroxyl Group ◽  
Side Chain ◽  
Compound C ◽  
Salvia Sclarea

The title compound, C20H36O2·CH3OH [systematic name: (3S)-4-[(S)-3-hydroxy-3-methylpent-4-en-1-yl]-3,4a,8,8-tetramethyldecahydronaphthalen-3-ol methanol monosolvate], is a methanol solvate of sclareol, a diterpene oil isolated from the medicinally important medicinal herb Salvia sclarea, commonly known as clary sage. It crystallizes in space group P1 (No. 1) with Z′ = 2. The sclareol molecule comprises two trans-fused cyclohexane rings, each having an equatorially oriented hydroxyl group, and a 3-methylpent-1-en-3-ol side chain. In the crystal, Os—H...Os, Os—H...Om, Om—H...Os and Om—H...Om (s = sclareol, m = methanol) hydrogen bonds connect neighboring molecules into infinite [010] chains. The title compound exhibits weak anti-leishmanial activity (IC50 = 66.4 ± 1.0 µM ml−1) against standard miltefosine (IC50 = 25.8 ± 0.2 µM ml−1).

(+)-3,12-Dioxo-5β-cholanic acid: hydrogen bonding in a diketo bile-acid derivative

2006 ◽  
Vol 62 (7) ◽  
pp. o2641-o2643 ◽  
Author(s):  
Elizabeth M. Kikolski ◽  
Mark Davison ◽  
Roger A. Lalancette ◽  
Hugh W. Thompson
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Bile Acid ◽  
Hydrogen Bonds ◽  
Side Chain ◽  
Asymmetric Unit ◽  
Independent Molecules ◽  
Chain Conformations ◽  
Cholanic Acid ◽  
Close Contacts

The asymmetric unit of the title crystal structure, C24H36O4, contains two independent molecules, differing only in their side-chain conformations and linked though O—H...O hydrogen bonds by carboxyl pairing [O...O = 2.6715 (17) and 2.6544 (17) Å; O—H...O = 170 and 179°]. Six intermolecular C—H...O=C close contacts were found.

Crystal structure of hydroxyzine dihydrochloride, C21H29ClN2O2Cl2

2018 ◽  
Vol 34 (1) ◽  
pp. 66-73
Author(s):  
Jordan A. Krueger ◽  
James A. Kaduk ◽  
Amy M. Gindhart ◽  
Thomas N. Blanton
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Powder Diffraction ◽  
Density Functional ◽  
Hydroxyl Group ◽  
Strong Hydrogen Bond ◽  
Side Chain ◽  
Powder Diffraction File ◽  
X Ray

The crystal structure of hydroxyzine dihydrochloride has been solved and refined using synchrotron X-ray powder diffraction data, and optimized using density functional techniques. Hydroxyzine dihydrochloride crystallizes in space group P21 (#4) with a = 11.48735(10), b = 7.41792(7), c = 14.99234(15) Å, β = 110.4383(10)°, V = 1197.107(13) Å3, and Z = 2. The hydroxyl-containing side chain of the cation is disordered over two conformations, with ~70/30% occupancy. The crystal structure consists of alternating polar (which includes the cation-anion interactions and hydrogen bonds) and nonpolar layers parallel to the ab-plane. The crystal structure is dominated by hydrogen bonds. Each of the protonated nitrogen atoms forms a very strong hydrogen bond to one of the chloride anions. The hydroxyl group forms a strong hydrogen bond to one of the chloride anions in both conformations, and there are subtle differences in the hydrogen bonding patterns between the conformations. The powder pattern is included in the Powder Diffraction File™ as entry 00-066-1603.

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.

scholarly journals Crystal structure of atazanavir, C38H52N6O7

2020 ◽  
Vol 35 (2) ◽  
pp. 129-135
Author(s):  
James A. Kaduk ◽  
Amy M. Gindhart ◽  
Thomas N. Blanton
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Powder Diffraction ◽  
Density Functional ◽  
Carbonyl Oxygen ◽  
Hydroxyl Group ◽  
Amide Nitrogen ◽  
Classical Hydrogen Bond ◽  
Intramolecular Hydrogen ◽  
Atazanavir Sulfate

The crystal structure of atazanavir has been solved and refined using synchrotron X-ray powder diffraction data and optimized using density functional techniques. Atazanavir crystallizes in space group P21 (#4) with a = 15.33545(7), b = 5.90396(3), c = 21.56949(13) Å, β = 96.2923(4)°, V = 1941.134(11) Å3, and Z = 2. Despite being labeled as “atazanavir sulfate”, the commercial reagent sample consisted of atazanavir free base. The structure consists of an array of extended-conformation molecules parallel to the ac-plane. Although the atazanavir molecule contains only four classical hydrogen bond donors, hydrogen bonding is, surprisingly, important to the crystal energy. Both intra- and intermolecular hydrogen bonds are significant. The hydroxyl group forms bifurcated intramolecular hydrogen bonds to a carbonyl oxygen atom and an amide nitrogen. Several amide nitrogens act as donors to the hydroxyl group and carbonyl oxygen atoms. An amide nitrogen acts as a donor to another amide nitrogen. Several methyl, methylene, methyne, and phenyl hydrogens participate in hydrogen bonds to carbonyl oxygens, an amide nitrogen, and the pyridine nitrogen. The powder pattern is included in the Powder Diffraction File™ as entry 00-065-1426.

Crystal structure of oxybutynin hydrochloride hemihydrate, C22H32NO3Cl(H2O)0.5

2019 ◽  
Vol 34 (1) ◽  
pp. 50-58
Author(s):  
James A. Kaduk ◽  
Nicholas C. Boaz ◽  
Amy M. Gindhart ◽  
Thomas N. Blanton
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Powder Diffraction ◽  
Density Functional ◽  
Hydroxyl Group ◽  
Layered Crystal ◽  
Powder Diffraction File ◽  
X Ray ◽  
Layered Crystal Structure ◽  
Oxybutynin Hydrochloride

The crystal structure of oxybutynin hydrochloride hemihydrate has been solved and refined using synchrotron X-ray powder diffraction data, and optimized using density functional techniques. Oxybutynin hydrochloride hemihydrate crystallizes in space group I2/a (#15) with a = 14.57266(8), b = 8.18550(6), c = 37.16842(26) Å, β = 91.8708(4)°, V = 4421.25(7) Å3, and Z = 8. The compound exhibits X-ray-induced photoreduction of the triple bond. Prominent in the layered crystal structure is the N–H⋅⋅⋅Cl hydrogen bond between the cation and anion, as well as O–H⋅⋅⋅Cl hydrogen bonds from the water molecule and hydroxyl group of the oxybutynin cation. C–H⋅⋅⋅Cl hydrogen bonds also contribute to the crystal energy, and help determine the conformation of the cation. The powder pattern is included in the Powder Diffraction File™ as entry 00-068-1305.

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