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On the Importance of Intermediate Internal Charge Repulsion for the Synthesis of Multifunctional Pores
Author(s) -
Baumeister Bodo,
Som Abhigyan,
Das Gopal,
Sakai Naomi,
Vilbois Francis,
Gerard David,
Shahi Shatrughan P.,
Matile Stefan
Publication year - 2002
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/1522-2675(200209)85:9<2740::aid-hlca2740>3.0.co;2-c
Subject(s) - chemistry , barrel (horology) , membrane , histidine , biophysics , crystallography , bilayer , molecule , counterion , transmembrane protein , ion , amino acid , biochemistry , organic chemistry , materials science , receptor , composite material , biology
Intermediate internal charge repulsion ( ICR ) is required to create synthetic pores with large, stable, transmembrane, and variably functionalized space. This conclusion is drawn from maximal transport and, in one case, catalytic activity of p ‐octiphenyl β ‐barrel pores with internal lysine, aspartate, and histidine residues around pH 7, 6, and 4.5, respectively. p K a Simulations corroborate the experimental correlation of intermediate ICR with activity and suggest that insufficient ICR causes pore ‘implosion' and excess ICR pore ‘explosion'. Esterolysis experiments support the view that the formation of stable space within multifunctional p ‐octiphenyl β ‐barrels requires more ICR in bilayer membranes than in H 2 O. Multivalency effects are thought to account for p ‐octiphenyl β ‐barrel expansion with increasing number of β ‐sheets, and proximity effects for unchanged pH profiles with increasing β ‐sheet length. Q‐TOF‐nano‐ESI‐MS barrel‐denaturation experiments indicate that contributions from internal counterion effects are not negligible. The overall characteristics of p‐ octiphenyl β ‐barrel pores with internal lysine, aspartate, and histidine residues, unlike de novo ‘ α ‐barrels' and similarly to certain biological channels, underscore the usefulness of rigid‐rod molecules to preorganize complex multifunctional supramolecular architecture.