Inhibition of acetylcholinesterase by physostigmine analogs: Conformational mobility of cysteine loop due to the steric effect of the alkyl chain

2002 ◽  
Vol 16 (2) ◽  
pp. 64-69 ◽  
Author(s):  
Enrico Gavuzzo ◽  
Massimo Pomponi
Keyword(s):  
Steric Effect ◽  
Alkyl Chain ◽  
Conformational Mobility

Squaraine chemistry. Synthesis of bis(4-dimethylaminophenyl)squaraine from dialkyl squarates. Mechanism and scope of the synthesis

1986 ◽  
Vol 64 (12) ◽  
pp. 2267-2273 ◽  
Author(s):  
Kock-Yee Law ◽  
F. Court Bailey
Keyword(s):  
Steric Effect ◽  
Alkyl Chain ◽  
Material Balance ◽  
Squaric Acid ◽  
Side Reactions ◽  
Key Factors ◽  
Product Analysis ◽  
Good Material ◽  
Two Factors ◽  
Optimized Conditions

The mechanism and the scope of the synthesis of bis(4-dialkylaminoaryl)squaraines from di-n-butyl squarate and N,N-dialkylanilines have been studied. Results show that water and acid are key factors of the synthesis, and these two factors have been optimized. Yields of squaraine are also found to be sensitive to the steric effect provided by the alkyl chain in dialkyl squarates as well as to the concentration of the aniline reagent used in the synthesis. Mechanistic results suggest that alkyl squarate is the precursor of the synthesis, and that squaraine is formed by diarylation of alkyl squarate with an N,N-dialkylaniline derivative. Under optimized conditions, a number of squaraines have been synthesized. Yields, which are comparable to those synthesized from squaric acid, are obtained. Product analysis with good material balance has been achieved, and results show that arylation and diarylation of the starting di-n-butyl squarate are major side reactions in the squaraine synthesis.

scholarly journals Interaction of dopamine β-mono-oxygenase with substituted imidazoles and pyrazoles. Catalysis and inhibition

1987 ◽  
Vol 242 (1) ◽  
pp. 227-233 ◽  
Author(s):  
S R Sirimanne ◽  
H H Herman ◽  
S W May
Keyword(s):  
Steric Effect ◽  
Alkyl Chain ◽  
Imidazole Ring ◽  
Amino Group ◽  
O2 Consumption ◽  
Methyl Substituent ◽  
Kinetic Behaviour ◽  
Substrate Analogues ◽  
Active Substrate ◽  
Terminal Amino

The interaction of dopamine beta-mono-oxygenase (DBM) with substrate analogues possessing either imidazole or pyrazole functionalities at the alkyl chain terminus was investigated. 1-(4-Hydroxybenzyl)imidazole (4-HOBI) is an active substrate for DBM, and it exhibits the expected ascorbate- and fumarate-dependencies and normal kinetic behaviour at concentrations up to 10 mM. 4-Hydroxybenzaldehyde was identified as the product formed from 4-HOBI on the basis of h.p.l.c. and g.c.-m.s. analysis, and its formation exhibits the expected 1:1 stoichiometry with O2 consumption. The 4-HOBI/DBM reaction is kinetically comparable with other DBM activities, and 4-HOBI is the first substrate analogue yet reported that exhibits substantial activity though lacking a terminal amino group. Introduction of a methyl substituent at the 2-position of the imidazole ring abolishes substrate activity, probably through a steric effect. 1-(4-Hydroxybenzyl)pyrazole, where imidazole is replaced by the isomeric pyrazole moiety, is a potent DBM inhibitor, and not a substrate. These results represent the first report of an active heterocyclic substrate or inhibitor for this enzyme, and establish the basis for the design of new classes of DBM substrates and inhibitors.

Steric effect and mobility of the alkyl chain in regio-irregular poly-3-alkylthiophenes

1999 ◽  
Vol 37 (15) ◽  
pp. 1763-1772 ◽  
Author(s):  
Chun-Guey Wu ◽  
Yii-Chung Lin ◽  
Mei-Jui Chan ◽  
Liang-Neng Chien
Keyword(s):  
Steric Effect ◽  
Alkyl Chain

Template mediated crystal engineering

1994 ◽  
Vol 52 ◽  
pp. 480-481
Author(s):  
Brigid R. Heywood ◽  
S. Champ
Keyword(s):  
Crystal Engineering ◽  
Electrostatic Interactions ◽  
Alkyl Chain ◽  
Crystallographic Axis ◽  
Two Dimensional ◽  
Engineering Process ◽  
Solution Interface ◽  
Extensive Program ◽  
Geometric Homology ◽  
Long Alkyl Chain

Recent work on the crystallisation of inorganic crystals under compressed monomolecular surfactant films has shown that two dimensional templates can be used to promote the oriented nucleation of solids. When a suitable long alkyl chain surfactant is cast on the crystallisation media a monodispersied population of crystals forms exclusively at the monolayer/solution interface. Each crystal is aligned with a specific crystallographic axis perpendicular to the plane of the monolayer suggesting that nucleation is facilitated by recognition events between the nascent inorganic solid and the organic template.For example, monolayers of the long alkyl chain surfactant, stearic acid will promote the oriented nucleation of the calcium carbonate polymorph, calcite, on the (100) face, whereas compressed monolayers of n-eicosyl sulphate will induce calcite nucleation on the (001) face, (Figure 1 & 2). An extensive program of research has confirmed the general principle that molecular recognition events at the interface (including electrostatic interactions, geometric homology, stereochemical complementarity) can be used to promote the crystal engineering process.

Dispersibility Evaluation of Graphene Oxides with Alkyl Chain Groups by Using Optical Transparency

2015 ◽  
Vol E98.C (2) ◽  
pp. 127-128 ◽  
Author(s):  
Asami OHTAKE ◽  
Seiko UCHINO ◽  
Kunio AKEDO ◽  
Masanao ERA ◽  
Koichi SAKAGUCHI
Keyword(s):  
Alkyl Chain ◽  
Optical Transparency ◽  
Graphene Oxides
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