A Noncovalent Approach to Antiparallel β-Sheet Formation

Abstract

Four tripeptide chains, when attached to the same end of a hydrogen-bonded duplex (1.2) with the unsymmetrical, complementary sequences of ADAA/DADD, have been brought into proximity, leading to the formation of four hybrid duplexes, 1a.2a, 1a.2b, 1b.2a, and 1b.2b, each of which contains a two-stranded beta-sheet segment. The extended conformations of the peptide chains were confirmed by 1D and 2D NMR. The peptide strands stay registered through hydrogen bonding and the beta-sheets are stabilized by side chain interactions. Two-dimensional NMR data also indicate that the duplex template prevents further aggregation in the peptide segment. When the peptide chains are attached to the two different termini of the duplex template, NMR studies show the presence of a mixture with no clearly defined conformations. In the absence of the duplex template, the tripeptides are found to associate randomly. Finally, isothermal titration calorimetry studies revealed that the hybrid duplex 1a.2a was more stable than either the duplex template or the peptides alone.

Strapped porphyrin rosettes based on the melamine–cyanuric acid motif. Self-assembly and supramolecular recognition

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] Because of its unique feature of directionality, specificity, and stability, hydrogen bonding has been one of the most versatile non-covalent forces for the self-assembly of well-defined supramolecular systems. [17][18][19][20][21] Over the years, a number of efficient triple and quadruple hydrogen bonding modes have been developed. [17][18][19] The triply hydrogen bonded melamine-cyanuric acid motif has been extensively studied for the formation of the so-called 'rosette' supramolecuar structures.…”

Preliminary mechanistic information on disulfide‐bond formation and the role of hydrogen bonds by nanoelectrospray mass spectrometry

“…1) chosen for the experiments were designed and synthesized by previous methods. 25,26,32,33 The coupling reactions were carried out by the standard peptide coupling methods and the resulting oligoamides contain 1,3-disubstituted benzene rings linked by˛-amino acid residues containing a variety of sequences using H-bonding donor (D) and acceptor (A) sites, i.e. amide O and H atoms.…”

Programmed assembly of rigid-rod ?-barrel pores: Thermal inversion of chirality

“…A thin film of EYPC (10 mg) was prepared by evaporating a solution in CHCl 3 and MeOH (0.5 ml each) on a rotary evaporator and then in vacuo (>2 h), and then hydrated with 0.6 ml buffer (>30 min, 10 mM K m H n PO 4 , 100 mM KCl, pH 6.4). The resulting suspension was subjected to >5 freeze-thaw cycles (using liquid N 2 to freeze and a warm water bath to thaw), >15 times extruded using a Mini-Extruder through a polycarbonate membrane (pore size 100 nm, Avanti), purified by gel filtration (Sephadex G-50) and diluted to 6 ml LUV stock solution.…”