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Toward catalytic rigid‐rod β‐barrels: A hexamer with multiple histidines
Author(s) -
Das Gopal,
Sakai Naomi,
Matile Stefan
Publication year - 2001
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.10034
Subject(s) - chemistry , random hexamer , tripeptide , barrel (horology) , guanidinium chloride , crystallography , histidine , stereochemistry , circular dichroism , amino acid , organic chemistry , biochemistry , enzyme , materials science , composite material
Rigid‐rod β‐barrels are composed of interdigitating, short, amphiphilic peptide strands that are flanked by stabilizing rigid‐rod “staves.” As a first step toward the construction of catalytic rigid‐rod β‐barrels, we here report synthesis and study of a new barrel designed to comprise alternating leucine and histidine residues at the inner and lysine and glutamate residues at the outer barrel surface. Synthesis of p ‐octiphenyls with lateral tripeptide strands followed procedures described previously. Barrel formation by programmed assembly of complementary tripeptide‐ p ‐octiphenyl rods was monitored by circular dichroism (CD). CD‐mixing curves (Job‐plots) were consistent with 1:1‐stoichiometry. Guanidinium chloride denaturation experiments gave a Δ G H20 = −1.8 kcal mol −1 with a C 50 = 1.9 M. Size exclusion chromatography suggested quantitative formation of a hexamer. Facile barrel deconstruction by acid and divalent cations demonstrated the presence of internal, nonproximal histidines. Inclusion complex formation with fluorescent guests corroborated internal hydrophobicity of β‐barrel hosts and potential for intratoroidal catalysis. Chirality 14:18–24, 2002. © 2002 Wiley‐Liss, Inc.