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Crystallographic observation of 'induced fit' in a cryptophane host-guest model system.

Taratula O, Hill PA, Khan NS, Carroll PJ, Dmochowski IJ - Nat Commun (2010)

Bottom Line: Cryptophane-A, comprised of two cyclotriguaiacylenes joined by three ethylene linkers, is a prototypal organic host molecule that binds reversibly to neutral small molecules via London forces.Of note are trifunctionalized, water-soluble cryptophane-A derivatives, which exhibit exceptional affinity for xenon in aqueous solution.Cryptophane internal volume varied by more than 20% across this series, which exemplifies 'induced fit' in a model host-guest system.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104, USA.

ABSTRACT
Cryptophane-A, comprised of two cyclotriguaiacylenes joined by three ethylene linkers, is a prototypal organic host molecule that binds reversibly to neutral small molecules via London forces. Of note are trifunctionalized, water-soluble cryptophane-A derivatives, which exhibit exceptional affinity for xenon in aqueous solution. In this paper, we report high-resolution X-ray structures of cryptophane-A and trifunctionalized derivatives in crown-crown and crown-saddle conformations, as well as in complexes with water, methanol, xenon or chloroform. Cryptophane internal volume varied by more than 20% across this series, which exemplifies 'induced fit' in a model host-guest system.

No MeSH data available.


Related in: MedlinePlus

Cryptophane hosts used in this study. Cryptophane-A, tripropargyl (1) and triallyl (2) derivatives are shown as single enantiomers.
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f1: Cryptophane hosts used in this study. Cryptophane-A, tripropargyl (1) and triallyl (2) derivatives are shown as single enantiomers.

Mentions: Here, we report X-ray crystal structures showing analogous induced fit in a cryptophane host–guest model system. Unlike many small-molecule host systems that have been characterized crystallographically to date, cryptophanes contain a three-dimensional hydrophobic cavity, which approximates many enzyme active sites. Because of minimal electrostatic interactions in these host–guest complexes, cryptophane binding is driven by favourable London forces. Cryptophane-A, tripropargyl (1) and triallyl (2) derivatives (Fig. 1) were crystallized with various encapsulated hydrophobic guests, including xenon. Notably, the cryptophane internal volume increased by more than 20% as the guest volume increased from methanol to chloroform.


Crystallographic observation of 'induced fit' in a cryptophane host-guest model system.

Taratula O, Hill PA, Khan NS, Carroll PJ, Dmochowski IJ - Nat Commun (2010)

Cryptophane hosts used in this study. Cryptophane-A, tripropargyl (1) and triallyl (2) derivatives are shown as single enantiomers.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3105606&req=5

f1: Cryptophane hosts used in this study. Cryptophane-A, tripropargyl (1) and triallyl (2) derivatives are shown as single enantiomers.
Mentions: Here, we report X-ray crystal structures showing analogous induced fit in a cryptophane host–guest model system. Unlike many small-molecule host systems that have been characterized crystallographically to date, cryptophanes contain a three-dimensional hydrophobic cavity, which approximates many enzyme active sites. Because of minimal electrostatic interactions in these host–guest complexes, cryptophane binding is driven by favourable London forces. Cryptophane-A, tripropargyl (1) and triallyl (2) derivatives (Fig. 1) were crystallized with various encapsulated hydrophobic guests, including xenon. Notably, the cryptophane internal volume increased by more than 20% as the guest volume increased from methanol to chloroform.

Bottom Line: Cryptophane-A, comprised of two cyclotriguaiacylenes joined by three ethylene linkers, is a prototypal organic host molecule that binds reversibly to neutral small molecules via London forces.Of note are trifunctionalized, water-soluble cryptophane-A derivatives, which exhibit exceptional affinity for xenon in aqueous solution.Cryptophane internal volume varied by more than 20% across this series, which exemplifies 'induced fit' in a model host-guest system.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104, USA.

ABSTRACT
Cryptophane-A, comprised of two cyclotriguaiacylenes joined by three ethylene linkers, is a prototypal organic host molecule that binds reversibly to neutral small molecules via London forces. Of note are trifunctionalized, water-soluble cryptophane-A derivatives, which exhibit exceptional affinity for xenon in aqueous solution. In this paper, we report high-resolution X-ray structures of cryptophane-A and trifunctionalized derivatives in crown-crown and crown-saddle conformations, as well as in complexes with water, methanol, xenon or chloroform. Cryptophane internal volume varied by more than 20% across this series, which exemplifies 'induced fit' in a model host-guest system.

No MeSH data available.


Related in: MedlinePlus