Erratum: correction: Antibacterial agents based on the cyclic d,l-α-peptide architecture

Abstract

1.7 A Ê with ARP 20 after 5% of the data had been set aside to calculate the free R-factor. Additional calculations were performed with the CCP4 suite of programs 21 . The model was re®ned with REFMAC 22 and water molecules were added with ARP. Model building was performed using the program O 23 . The ®nal model has been re®ned at 1.7 A Ê to an R-factor of 0.175 with an R free of 0.208 (Table 1). ATP and acyl-adenylate complexesCrystals of the apo complex were soaked for 24 h in a solution consisting of 1.7 M Li 2 SO 4 , 100 mM HEPES, pH 7.5, and 20 mM ATP. Diffraction data were collected at beamline X26C (99.7% complete, 6.3-fold redundancy, R sym = 12.9%), and the structure was solved using difference Fourier methods. The ATP-bound model has been re®ned at 2.9 A Ê to an R-factor of 0.203 (R free = 0.267). No water molecules were added owing to the limited resolution. Residues 167±188 and 241±248 appear to be disordered, including the zincbinding motifs and the previously missing surface loop of MoeB. In the apo complex, the polypeptide segments containing the zinc-binding motifs have higher average B-factors compared with the remainder of the molecule. At 2.9 A Ê the quality of the electron density maps for the ATP complex is reduced making it impossible to observe these more mobile regions. To obtain the acyl-adenylate complex, apo crystals were soaked for 24 h in a solution consisting of 1.7 M Li 2 SO 4 , 100 mM HEPES, pH 7.5, 20 mM ATP, and 20 mM MgSO 4 . Diffraction data were collected at beamline X26C (98.7% complete, 3.5-fold redundancy, R sym = 8.6%), and the structure was solved using difference Fourier methods. The acyl-adenylate model has been re®ned at 2.1 A Ê resolution to an R-factor of 0.188 (R free = 0.225) following the same protocol described for the apo complex. The residues in the zinc-binding motif of MoeB are present in the electron density maps in a conformation identical to that found in the apo complex, but residues 182±188 are again disordered.

Strategies for Fine-Tuning the Conformations of Cyclic Peptides

“…102,103 Such nanotubes are robust enough to survive within a biological milieu; the nanotubes can even insert into cell membranes and function as passive ion channels, 104 a property that leads to antibacterial activity. 105,106 3.1.3. All-D Cyclic Peptides.…”

Chloride Transport through Supramolecular Barrel-Rosette Ion Channels: Lipophilic Control and Apoptosis-Inducing Activity

“…The robust chemical nature and adaptable ion transport behavior with the aid of structural manipulation have made artificial ion transport systems a convenient subject of research, compared to their natural congeners. Various strategic designs have been introduced, based on either unimolecular or self-assembled architecture, for the artificial ion channel formation. − Crown ether based unimolecular hydraphile channels reported by Gokel , and cyclic peptide based self-assembled ion channels reported by Ghadiri have already promised antibacterial activity against Gram-negative and Gram-positive bacteria. These ion channels undergo a rapid and selective cell death of bacteria by collapsing the transmembrane ion potential by transporting cations.…”

Formation of nanophases in epoxy thermosets containing an organic–inorganic macrocyclic molecular brush with poly(ε-caprolactone)-block-polystyrene side chains

“…During the past years, numerous cyclic molecular brushes have been synthesized; their structure and properties were extensively investigated. [38][39][40][41][42][43] Depending on the type and size of both cyclic backbones and side chains, cyclic molecular brushes can display a variety of microstructures and properties, which have potential applications in various aspects. For instance, Ghadiri and co-workers 43 reported the synthesis of a medium-sized cyclic polypeptide grafted by long chains and the cyclic molecular brushes showed potential applications in ion transport across the membrane, since they displayed the architecture of nanotubes via the stacking of cyclic polypeptides.…”

“…[38][39][40][41][42][43] Depending on the type and size of both cyclic backbones and side chains, cyclic molecular brushes can display a variety of microstructures and properties, which have potential applications in various aspects. For instance, Ghadiri and co-workers 43 reported the synthesis of a medium-sized cyclic polypeptide grafted by long chains and the cyclic molecular brushes showed potential applications in ion transport across the membrane, since they displayed the architecture of nanotubes via the stacking of cyclic polypeptides. Recently, there has been ample literature reporting on the preparation of macrocyclic molecular brushes by the use of macrocyclic polymers as backbones, and homopolymers or amphiphilic block copolymers as side chains, to modulate the architectures to afford versatile properties.…”