scholarly journals Incorporation of an Intramolecular Hydrogen-Bonding Motif in the Side Chain of 4-Aminoquinolines Enhances Activity against Drug-ResistantP.falciparum

2006 ◽  
Vol 49 (15) ◽  
pp. 4535-4543 ◽  
Author(s):  
Peter B. Madrid ◽  
Ally P. Liou ◽  
Joseph L. DeRisi ◽  
R. Kiplin Guy
Keyword(s):  
Hydrogen Bonding ◽  
Intramolecular Hydrogen Bonding ◽  
Side Chain ◽  
Intramolecular Hydrogen

Structure and Conformations of Gaba-Transaminase Inhibitors. I. Multisubstrate Analogs

1986 ◽  
Vol 39 (10) ◽  
pp. 1559
Author(s):  
PR Andrews ◽  
V Cody ◽  
MN Iskander ◽  
AI Jeffrey ◽  
MF Mackay ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Transition State ◽  
Intramolecular Hydrogen Bonding ◽  
Side Chain ◽  
Gaba Transaminase ◽  
X Ray ◽  
Potential Energy Calculations ◽  
Phenolic Oxygen ◽  
Structural Differences ◽  
Intramolecular Hydrogen

Two multisubstrate analogues of the transition state in the reaction catalysed by the enzyme GABA- transaminase (E.C. 2.6.1.19), sulfonic acid pyridoxal dervative , C10H16N2O5S (1) and carboxylic acid pyridoxal derivative, C13H18N2O4 (2), have been characterized by X-ray analyses of crystals of (1). HCl , (1).H2O and (2). HCl . In each structure, the nitrogen on the side chain is the donor in intramolecular hydrogen bonding. However, it is only in (2). HCl that this interaction is with the phenolic oxygen as postulated in the proposed transition state of the reaction catalysed by GABA- transaminase . For both structures of (1), on the other hand, this interaction is with the oxygen of the ring hydroxymethyl substituent, and results in a seven- membered ring. Conformational analysis indicates that both modes of hydrogen bonding may be present in the pyridoxal derivatives, although no quantitative assessment is possible at the MINDO/3 or MNDO levels. Simple classical potential energy calculations indicate significant structural differences between the lowest energy conformations of these compounds and the calculated transition state. However, conformations which match the key features of the transition state are also relatively low in energy.

scholarly journals Incorporation of an intramolecular hydrogen bonding motif in the side chain of antimalarial benzimidazoles

MedChemComm ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 450-455 ◽  
Author(s):  
Henrietta D. Attram ◽  
Sergio Wittlin ◽  
Kelly Chibale
Keyword(s):  
Plasmodium Falciparum ◽  
Hydrogen Bonding ◽  
Malaria Parasite ◽  
Intramolecular Hydrogen Bonding ◽  
Side Chain ◽  
Drug Resistant ◽  
Human Malaria Parasite ◽  
Human Malaria ◽  
Intramolecular Hydrogen

Analogues of a novel class of benzimidazoles with an intramolecular hydrogen bonding motif have been synthesized and evaluated in vitro for their antiplasmodium activity against chloroquine-sensitive (NF54) and multi-drug resistant (K1) strains of the human malaria parasite Plasmodium falciparum.

scholarly journals Intramolecular Hydrogen Bonding in Isotactic Poly(methacrylamide)s and Its Implications for Control of Side-Chain Orientation

1997 ◽  
Vol 29 (8) ◽  
pp. 701-704 ◽  
Author(s):  
Takayuki Nakahira ◽  
Fan Lin ◽  
Cham Tau Boon ◽  
Takeshi Karato ◽  
Masahiko Annaka ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Intramolecular Hydrogen Bonding ◽  
Side Chain ◽  
Chain Orientation ◽  
Intramolecular Hydrogen ◽  
Side Chain Orientation

Peptide model XXVIII: An exploratory ab initio and density functional study on the side-chain-backbone interaction in N-acetyl-L-cysteine- N-methylamide and N-formyl-L-cysteinamide in their γL-backbone conformations

2002 ◽  
Vol 80 (7) ◽  
pp. 832-844 ◽  
Author(s):  
M A Zamora ◽  
H A Baldoni ◽  
A M Rodriguez ◽  
R D Enriz ◽  
C P Sosa ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Potential Energy ◽  
Potential Energy Surface ◽  
Ab Initio ◽  
Energy Surface ◽  
Geometry Optimization ◽  
Intramolecular Hydrogen Bonding ◽  
Functional Study ◽  
Side Chain ◽  
Intramolecular Hydrogen

A conformational and electronic study on the energetically preferred conformations (γL) of N- and C-protected L-cysteine (P-CONH-CH(CH2SH)-CONH-Q, where P and Q may be H or Me) was carried out. After restraining the backbone (BB) conformation to its global minimum (γL or C7eq), all nine possible side-chain (SC) conformations were subjected to geometry optimization at the HF/3–21G and the B3LYP/6–31G(d,p) levels of theory. Seven of the nine side-chain conformers were located on the potential-energy surface. All conformers were subjected to an AIM (atoms in molecules) analysis. This study indicates that three of the seven optimized conformers exhibited either or both SC [Formula: see text] BB- or BB [Formula: see text] SC-type intramolecular hydrogen bonding. Five conformers, however, had distances between a proton and a heteroatom that suggested hydrogen bonding.Key words: L-cysteine diamides, side-chain potential-energy surface, ab initio and DFT geometry optimization, AIM analysis, intramolecular hydrogen bonding.

scholarly journals Multicentered hydrogen bonding in 1-[(1-deoxy-β-D-fructopyranos-1-yl)azaniumyl]cyclopentanecarboxylate (`D-fructose-cycloleucine')

2019 ◽  
Vol 75 (8) ◽  
pp. 1096-1101 ◽  
Author(s):  
Valeri V. Mossine ◽  
Charles L. Barnes ◽  
Thomas P. Mawhinney
Keyword(s):  
Hydrogen Bonding ◽  
Intramolecular Hydrogen Bonding ◽  
Side Chain ◽  
Slow Rotation ◽  
H Nmr ◽  
Compound C ◽  
Nmr Data ◽  
Cyclopentane Ring ◽  
Intramolecular Hydrogen ◽  
Hydroxy Groups

The title compound, C12H21NO7, (I), is conformationally unstable; the predominant form present in its solution is the β-pyranose form (74.3%), followed by the β- and α-furanoses (12.1 and 10.2%, respectively), α-pyranose (3.4%), and traces of the acyclic carbohydrate tautomer. In the crystalline state, the carbohydrate part of (I) adopts the 2 C 5 β-pyranose conformation, and the amino acid portion exists as a zwitterion, with the side chain cyclopentane ring assuming the E 9 envelope conformation. All heteroatoms are involved in hydrogen bonding that forms a system of antiparallel infinite chains of fused R 3 3(6) and R 3 3(8) rings. The molecule features extensive intramolecular hydrogen bonding, which is uniquely multicentered and involves the carboxylate, ammonium and carbohydrate hydroxy groups. In contrast, the contribution of intermolecular O...H/H...O contacts to the Hirshfeld surface is relatively low (38.4%), as compared to structures of other D-fructose-amino acids. The 1H NMR data suggest a slow rotation around the C1—C2 bond in (I), indicating that the intramolecular heteroatom contacts survive in aqueous solution of the molecule as well.

scholarly journals Effects of Side-Chain Structure and Solvent on Intramolecular Hydrogen Bonding in Isotactic Poly(methacrylamide)s

1998 ◽  
Vol 30 (11) ◽  
pp. 910-914 ◽  
Author(s):  
Takayuki Nakahira ◽  
Lin Fan ◽  
Cham Tau Boon ◽  
Takayuki Fukada ◽  
Takeshi Karato ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Intramolecular Hydrogen Bonding ◽  
Chain Structure ◽  
Side Chain ◽  
Intramolecular Hydrogen
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