scholarly journals Molecular Recognition by Pillar[5]arenes: Balance Between Hydrophobic and Electrostatic Interactions

2021 ◽  
Author(s):  
B. Gómez-González ◽  
L. García-Río ◽  
N. Basilio ◽  
J.C. Mejuto ◽  
J. Simal-Gandara
Keyword(s):  
Molecular Recognition ◽  
Inclusion Complexes ◽  
Electrostatic Interactions ◽  
Alkyl Chain ◽  
Binding Constants ◽  
Ionic Interactions ◽  
Hydrophobic Character

The formation of inclusion complexes between alkylsulfonate guests and a cationic pillar[5]arene receptor in water was investigated by NMR and ITC techniques. The results show the formation of host-guest complexes stabilized by electrostatic interactions and hydrophobics effects with binding constants of up to 107 M-1 for the guest with higher hydrophobic character. Structurally, the alkyl chain of the guest is included in the hydrophobic aromatic cavity of the macrocycle while the sulfonate groups are hold in the multicationic portal by ionic interactions.

scholarly journals Molecular Recognition by Pillar[5]arenes: Evidence for Simultaneous Electrostatic and Hydrophobic Interactions

Pharmaceutics ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 60
Author(s):  
Borja Gómez-González ◽  
Luis García-Río ◽  
Nuno Basílio ◽  
Juan C. Mejuto ◽  
Jesus Simal-Gandara
Keyword(s):  
Molecular Recognition ◽  
Inclusion Complexes ◽  
Electrostatic Interactions ◽  
Alkyl Chain ◽  
Hydrophobic Interactions ◽  
Binding Constants ◽  
Ionic Interactions ◽  
Hydrophobic Effects ◽  
Hydrophobic Character ◽  
Electrostatic And Hydrophobic Interactions

The formation of inclusion complexes between alkylsulfonate guests and a cationic pillar[5]arene receptor in water was investigated by NMR and ITC techniques. The results show the formation of host-guest complexes stabilized by electrostatic interactions and hydrophobic effects with binding constants of up to 107 M−1 for the guest with higher hydrophobic character. Structurally, the alkyl chain of the guest is included in the hydrophobic aromatic cavity of the macrocycle while the sulfonate groups are held in the multicationic portal by ionic interactions.

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.

scholarly journals Distinctive Supramolecular Features of β-Cyclodextrin Inclusion Complexes with Antidepressants Protriptyline and Maprotiline: A Comprehensive Structural Investigation

2021 ◽  
Vol 14 (8) ◽  
pp. 812
Author(s):  
Thammarat Aree
Keyword(s):  
Inclusion Complexes ◽  
Density Functional ◽  
Water Solubility ◽  
Geometry Optimization ◽  
Binding Constants ◽  
Basis Set ◽  
Full Geometry Optimization ◽  
Basis Set Superposition Error ◽  
X Ray ◽  
Molecular Stability

Depression, a global mental illness, is worsened due to the coronavirus disease 2019 (COVID-2019) pandemic. Tricyclic antidepressants (TCAs) are efficacious for the treatment of depression, even though they have more side effects. Cyclodextrins (CDs) are powerful encapsulating agents for improving molecular stability, water solubility, and lessening the undesired effects of drugs. Because the atomic-level understanding of the β-CD–TCA inclusion complexes remains elusive, we carried out a comprehensive structural study via single-crystal X-ray diffraction and density functional theory (DFT) full-geometry optimization. Here, we focus on two complexes lining on the opposite side of the β-CD–TCA stability spectrum based on binding constants (Kas) in solution, β-CD–protriptyline (PRT) 1—most stable and β-CD–maprotiline (MPL) and 2—least stable. X-ray crystallography unveiled that in the β-CD cavity, the PRT B-ring and MPL A-ring are aligned at a nearly perfect right angle against the O4 plane and primarily maintained in position by intermolecular C–H···π interactions. The increased rigidity of the tricyclic cores is arising from the PRT -CH=CH- bridge widens, and the MPL -CH2–CH2- flexure narrows the butterfly angles, facilitating the deepest and shallower insertions of PRT B-ring (1) and MPL A-ring (2) in the distorted round β-CD cavity for better complexation. This is indicated by the DFT-derived complex stabilization energies (ΔEstbs), although the complex stability orders based on Kas and ΔEstbs are different. The dispersion and the basis set superposition error (BSSE) corrections were considered to improve the DFT results. Plus, the distinctive 3D arrangements of 1 and 2 are discussed. This work provides the first crystallographic evidence of PRT and MPL stabilized in the β-CD cavity, suggesting the potential application of CDs for efficient drug delivery.

scholarly journals Unexpected Specificity within Dynamic Transcriptional Protein-Protein Complexes

2020 ◽  
Author(s):  
Matthew J. Henley ◽  
Brian M. Linhares ◽  
Brittany S. Morgan ◽  
Tomasz Cierpicki ◽  
Carol A. Fierke ◽  
...  
Keyword(s):  
Molecular Recognition ◽  
Electrostatic Interactions ◽  
Protein Complexes ◽  
Critical Role ◽  
Gene Activation ◽  
Disordered Proteins ◽  
Conformational Ensemble ◽  
Regulation Of Transcription ◽  
Protein Protein Interaction ◽  
Eukaryotic Gene

AbstractA key functional event in eukaryotic gene activation is the formation of dynamic protein-protein interaction networks between transcriptional activators and transcriptional coactivators. Seemingly incongruent with the tight regulation of transcription, many biochemical and biophysical studies suggest that activators use nonspecific hydrophobic and/or electrostatic interactions to bind to coactivators, with few if any specific contacts. Here a mechanistic dissection of a set of representative dynamic activator•coactivator complexes, comprised of the ETV/PEA3 family of activators and the coactivator Med25, reveals a different molecular recognition model. The data demonstrate that small sequence variations within an activator family significantly redistribute the conformational ensemble of the complex while not affecting overall affinity, and distal residues within the activator—not often considered as contributing to binding—play a key role in mediating conformational redistribution. The ETV/PEA3•Med25 ensembles are directed by specific contacts between the disordered activator and the Med25 interface, which is facilitated by structural shifts of the coactivator binding surface. Taken together, these data highlight the critical role coactivator plasticity plays in recognition of disordered activators, and indicates that molecular recognition models of disordered proteins must consider the ability of the binding partners to mediate specificity.

scholarly journals The interaction of methanol dehydrogenase and cytochrome cL in the acidophilic methylotroph Acetobacter methanolicus

1991 ◽  
Vol 280 (1) ◽  
pp. 139-146 ◽  
Author(s):  
H T C Chan ◽  
C Anthony
Keyword(s):  
Electrostatic Interactions ◽  
High Ionic Strength ◽  
Methanol Dehydrogenase ◽  
Beta Subunit ◽  
Ionic Interactions ◽  
Oxidoreductase Activity ◽  
Strength Of Interaction ◽  
Lysine Residues ◽  
Arginine Residues ◽  
Cytochrome Cl

The quinoprotein methanol dehydrogenase (MDH) of Acetobacter methanolicus has an alpha 2 beta 2 structure. By contrast with other MDHs, the beta-subunit (approx. 8.5 kDa) does not contain the five lysine residues previously proposed to be involved in ionic interactions with the electron acceptor cytochrome cL. That electrostatic interactions are involved was confirmed by the demonstration that methanol:cytochrome cL oxidoreductase activity was inhibited by high ionic strength (I), the strength of interaction being inversely related to the square root of I. Specific modifiers of arginine residues on MDH inhibited this reaction but not the dye-linked MDH activity. Modification of lysine residues on MDH that altered its charge had no effect on the dye-linked activity but inhibited reaction with cytochrome cL. When the charge was retained on modification of lysine residues, little effect on either activity was observed. Cross-linking experiments confirmed that lysine residues on the alpha-subunit, but not the beta-subunit, are involved in the ‘docking’ process between the proteins.

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