Accurate reproduction of the mechanism peptide folding in solution and conformational preferences as a function amino acid sequence is possible with atomic level dynamics simulations. For example, simulations correctly predict left-handed 31-helical fold for β-heptapeptide 1 (the molecular model shown picture) right-handed helical β-hexapeptide 2, was confirmed by NMR spectroscopy.

Abstract Bacteria release membrane vesicles (MVs) that play important roles in various biological processes. However, the mechanisms of MV formation Gram-positive bacteria are unclear, as these cells possess a single cytoplasmic is surrounded by thick cell wall. Here we use live imaging and electron cryo-tomography to describe mechanism for Bacillus subtilis . We show expression prophage-encoded endolysin sub-population generates holes peptidoglycan Through openings, material protrudes into...

Abstract Enantiomerically pure β‐amino‐acid derivatives with the side chains of Ala, Val, and Leu in 2‐ or 3‐position (β 2 ‐ β 3 ‐amino acids, resp.), as well substituents both 3‐positions 2,3 like ‐configuration) have been prepared (compounds 8 – 17 ) incorporated (by stepwise synthesis fragment coupling, intermediates 24 34 into β‐hexa‐, β‐hepta‐, β‐dodecapeptides ( 1 ). The new some previously β‐peptides 35 39 showed NH/ND exchange rates (in MeOH at room temperature) τ 1/2 values up to 60...

Components of a toolbox with predictable secondary structural elements: β-peptides. The β-peptide shown here proteinogenic side chains adopts parallel pleated sheet structure in the solid state upon incorporation suitably configured β-amino acids. When β-dipeptide turn segment is incorporated center, hairpin formed solution.

This review presents natural products from cyanobacteria. Several classes of secondary metabolites are highlighted. Toxic these prokaryotic photosynthetic organisms include compounds such as microcystin, anatoxin and saxitoxin, which display hepatotoxicity neurotoxicity. Their potential drugs in cancer therapy is discussed based on the cryptophycin class potent cytotoxic agents. The next part this highlights iron chelators cyanobacteria, including schizokinen, synechobactin anachelin....

Abstract For a comparison with the corresponding α‐ and β‐hexapeptides H‐(Val‐Ala‐Leu) 2 ‐OH (A) H‐(β‐HVal‐β‐HAla‐β‐HLeu) ( B ), we have now prepared γ‐hexapeptide 1 built from homochirally similar S )‐4‐aminobutanoic acid, R )‐4‐amino‐5‐methylhexanoic )‐4‐amino‐6‐methylheptanoic acid. The precursors were either by double Arndt ‐ Eistert homologation of protected amino acids Boc‐Val‐OH, Boc‐Ala‐OH, Boc‐Leu‐OH Schemes or superior route involving olefination/hydrogenation aldehydes...

Oligomers of -amino acids ( -peptides), which are readily available by standard meth­ ods either in solution or on solid support, adopt a large variety different secondary structures and the state. -Peptides 4, 5 10 fold into helix with 3 residues per turn 14-membered H-bonded rings (314 helix) that is left-handed for right-handed 2 (due to reversal chirality building blocks), as was clearly demonstrated two-dimensional NMR-spectroscopy. This thermally very stable methanol upon heating. As...

The structural and thermodynamic properties of a 6-residue β-peptide that was designed to form hairpin conformation have been studied by NMR spectroscopy MD simulation in methanol solution. predicted would be characterized 10-membered hydrogen-bonded turn involving residues 3 4, two extended antiparallel strands. interproton distances backbone torsional dihedral angles derived from the experiments at room temperature are general terms compatible with conformation. Two trajectories system...

Straightforward access to useful synthetic intermediates is provided by this new method. Simple, α,β-unsaturated aldehydes are excellent substrates in the hetero-Diels–Alder reaction with inverse electron demand, catalyzed CrIII–Schiff base complexes (see scheme; R1, R2=alkyl or aryl) presence of 4-Å molecular sieves and no solvent. The resulting dihydropyrans obtained high enantio- (89–98 % ee) diastereoselectivity (>95 de) yield (40–95 %).

Short β-peptides can mimic natural peptide hormones, as has been shown with a cyclo-β-tetrapeptide (1) that displays micromolar affinity to human somatostatin receptors. β-Peptides are thus promising new class of peptidomimetics potential high bioavailability due their excellent resistance against proteases.

We have investigated five different poly(ethylene glycol) (PEG, 5 kDa) catechol derivatives in terms of their spontaneous surface assembly from aqueous solution, adlayer stability, and resistance to nonspecific blood serum adsorption as a function the type catechol-based anchor, conditions (temperature, pH), substrate (SiO(2), TiO(2), Nb(2)O(5)). Variable-angle spectroscopic ellipsometry (VASE) was used for layer thickness evaluation, X-ray photoelectron spectroscopy (XPS) composition,...

Abstract Members of the diazeniumdiolate class natural compounds show potential for drug development because their antifungal, antibacterial, antiviral, and antitumor activities. Yet, biosynthesis has remained elusive to date. Here, we identify a gene cluster directing compound fragin in Burkholderia cenocepacia H111. We provide evidence that is metallophore metal chelation molecular basis its antifungal activity. A subset biosynthetic genes involved synthesis previously undescribed...

Abstract β‐Hexapeptides 1–5 and a β‐dodecapeptide 6 with sequences containing two different types of β‐amino acids (aliphatic proteinageous side chains in the 2‐ or 3‐position) have been prepared. CD ( Fig. 1 ) NMR measurements indicate that, one exception, secondary structures formed by these new β‐peptides differ from those isomers studied previously. Detailed analysis β‐hexapeptide 5 (with alternating β 2 ,β 3 ‐building blocks) molecular‐dynamics simulations produced minimum energy...

beta-Peptides with side chains in the 2- and 3-positions on neighboring residues (of (S) configuration) are known to fold form a turn (similar an alpha-peptidic beta-turn). Thus, we have synthesized appropriately substituted beta-tetrapeptide derivative mimic hormone somatostatin its binding human receptors hsst(1-5), which is rest upon containing amino acid Thr, Lys, Trp, Phe. The N-acetyl-peptide amide Ac-beta(3)-HThr-beta(2)-HLys-beta(3)-HTrp-beta(3)-HPhe-NH(2) (1) indeed shows all...

Siderophores are natural iron chelators that have been evolutionarily selected to bind Fe ions with very high binding constants. We utilize these unique properties metal oxide surfaces using a fragment of the cyanobacterial siderophore anachelin. The resulting poly(ethylene glycol) conjugate forms stable adlayers on TiO2 as has shown by variable angle spectroscopic ellipsometry and X-ray photoelectron spectroscopy. Moreover, coated highly protein-resistant against adsorption full human serum.

Two new modified hexacyclopeptides, aerucyclamides A and B, were isolated from the toxic freshwater cyanobacterium Microcystis aeruginosa PCC 7806. The constitution was assigned by spectroscopic methods, configuration determined chemical degradation analysis Marfey's method combined with synthesis. Synthetic aerucyclamide B obtained through oxidation of (MnO2, benzene). found to be crustacean Thamnocephalus platyurus, exhibiting LC50 values for congeners 30.5 33.8 microM, respectively.

Aerucyclamides C and D were isolated from the cyanobacterium Microcystis aeruginosa PCC 7806, their structures established by NMR spectroscopy chemical transformation degradation. Acidic hydrolysis of aerucyclamide (CF3CO2H, H2O) resulted in microcyclamide 7806A. This evidence combined with spectroscopic physical data suggest a structure revision for 7806A, which incorporates an O-acylated Thr ammonium residue instead originally proposed methyl oxazoline ring. We have prepared 7806B upon...

Nonfouling coatings, based on surface-tethered, hydrophilic polymer chains, have widespread application in areas such as biosensing, medical devices, and biotechnology. Self-organization of polymers is a particularly attractive approach given its simplicity cost-effectiveness the application. Here we present new class polycationic poly(l-lysine)-graft-poly(ethylene glycol) copolymer (PLL-g-PEG) with fraction amine-terminated lysine side chains covalently conjugated to...

The preparation of the polyketide natural products anguinomycin C and D is reported based on key steps such as Negishi stereoinversion cross coupling, Jacobsen Cr(III)-catalyzed Hetero Diels-Alder reaction, Evans B-mediated syn-aldol chemistry, B-alkyl Suzuki-Miyaura coupling. configuration both was established (5R,10R,16R,18S,19R,20S). Biological evaluation demonstrated that these are inhibitors nuclear export receptor CRM1, leading to shutdown CRM1-mediated protein at concentrations above...

The isolation and structure of cyanopeptolin 1020 (hexanoic acid-Glu-N[-O-Thr-Arg-Ahp-Phe-N-Me-Tyr-Val-]) from a Microcystis strain is reported. Very potent picomolar trypsin inhibition (IC50 = 670 pM) low nanomolar values against human kallikrein (4.5 nM) factor XIa (3.9 have been determined for 1020. For plasmin chymotrypsin, micromolar concentrations were necessary 50% inhibition. Cyanopeptolin was found to be toxic the freshwater crustacean Thamnocephalus platyurus (LC50 8.8 μM), which...

Unus pro omnibus: The development of compounds inducing neurite outgrowth might constitute a valuable approach for the non-invasive medical treatment neurodegenerative diseases. With aid bifunctional building block, total syntheses group pyridone polyenes originally produced by entomopathogenic fungi was achieved (see picture). All these natural products displayed neuritogenic activity in PC-12 cell line.