Conformational stability studies of a stapled hexa-β3-peptide library.

A library of 14-helical hexa β(3)-peptides was synthesized in order to determine the influence of sequence variation as well as staple size and location on conformational stability. From this study we show that appropriately stapled hexa-β(3)-peptides can allow for a number of variations without significant perturbation of the 14-helix.

A single beta-amino acid substitution to angiotensin II confers AT2 receptor selectivity and vascular function.

Novel AT(2)R ligands were designed by substituting individual β-amino acid in the sequence of the native ligand angiotensin II (Ang II). Relative ATR selectivity and functional vascular assays (in vitro AT(2)R-mediated vasorelaxation and in vivo vasodepressor action) were determined. In competition binding experiments using either AT(1)R- or AT(2)R- transfected HEK-293 cells, only β-Asp(1)-Ang II and Ang II fully displaced [(125)I]-Ang II from AT(1)R.

Effect of acyl chain structure and bilayer phase state on binding and penetration of a supported lipid bilayer by HPA3.

The effect of acyl chain structure and bilayer phase state on binding and penetration by the peptide HPA3 was studied using dual polarisation interferometry. This peptide is an analogue of Hp(2-20) derived from the N-terminus of Helicobacter pylori ribosomal protein L1 (RpL1) which has been shown to have antimicrobial and cell-penetrating properties. The binding of HPA3 to zwitterionic 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) or 1-palmitolyl-2-oleyl-sn-glycero-3-phosphocholine (POPC) and negatively charged membranes composed of DMPC and 1,2-dimyristoyl-sn-glycero-3-(phosphor-rac-(1-glycerol)) (DMPG) or POPC and 1-palmitolyl-2-oleyl-sn-glycero-3-(phosphor-rac-(1-glycerol)) (POPG) was determined using dual polarisation interferometry (DPI).

β-Amino acid substitution to investigate the recognition of angiotensin II (AngII) by angiotensin converting enzyme 2 (ACE2).

In spite of the important role of angiotensin converting enzyme 2 (ACE2) in the cardiovascular system, little is known about the substrate structural requirements of the AngII-ACE2 interaction. Here we investigate how changes in angiotensin II (AngII) structure affect binding and cleavage by ACE2. A series of C3 β-amino acid AngII analogs were generated and their secondary structure, ACE2 inhibition, and proteolytic stability assessed by circular dichroism (CD), quenched fluorescence substrate (QFS) assay, and LC-MS analysis, respectively.

The membrane insertion of helical antimicrobial peptides from the N-terminus of Helicobacter pylori ribosomal protein L1.

The interaction of two helical antimicrobial peptides, HPA3 and HPA3P with planar supported lipid membranes was quantitatively analysed using two complementary optical biosensors. The peptides are analogues of Hp(2-20) derived from the N-terminus of Helicobacter pylori ribosomal protein L1 (RpL1). The binding of these two peptide analogues to zwitterionic dimyristoyl-phosphatidylcholine (DMPC) and negatively charged membranes composed of DMPC/dimyristoylphosphatidylglycerol (DMPG) (4:1) was determined using surface plasmon resonance (SPR) and dual polarisation interferometry (DPI).

Synthesis of stapled beta3-peptides through ring-closing metathesis.

The first synthesis of carbon-stapled beta(3)-peptides is reported. The precursor beta(3)-peptides, with O-allyl beta-serines located in an i/i+3 relationship, were prepared on solid phase. We show that efficient ring-closing metathesis (RCM) of these new beta(3)-peptides proceeds smoothly either in solution or on an appropriate solid support.

The beta-amyloid protein of Alzheimer's disease increases neuronal CRMP-2 phosphorylation by a Rho-GTP mechanism.

Neuritic abnormalities are a major hallmark of Alzheimer's disease (AD) pathology. Accumulation of beta-amyloid protein (Abeta) in the brain causes changes in neuritic processes in individuals with this disease. In this study, we show that Abeta decreases neurite outgrowth from SH-SY5Y human neuroblastoma cells.

The beta-amyloid protein of Alzheimer's disease binds to membrane lipids but does not bind to the alpha7 nicotinic acetylcholine receptor.

Accumulation of the amyloid protein (Abeta) in the brain is an important step in the pathogenesis of Alzheimer's disease. However, the mechanism by which Abeta exerts its neurotoxic effect is largely unknown. It has been suggested that the peptide can bind to the alpha7 nicotinic acetylcholine receptor (alpha7nAChR).

Evaluation of the membrane-binding properties of the proximal region of the angiotensin II receptor (AT1A) carboxyl terminus by surface plasmon resonance.

The proximal region of the angiotensin II receptor (AT1A) carboxyl-terminus (known as helix VIII) is important for receptor function. In this study, we used surface plasmon resonance (SPR) to examine the interaction of helix VIII-derived peptides with three model lipid membranes. The membrane-binding properties of these synthetic peptides, as well as a series of peptide analogues with modified amino acid sequences, could be explained by both amino acid sequence and kinetic binding data by SPR.

Cholesterol is necessary both for the toxic effect of Abeta peptides on vascular smooth muscle cells and for Abeta binding to vascular smooth muscle cell membranes.

Accumulation of beta amyloid (Abeta) in the brain is central to the pathogenesis of Alzheimer's disease. Abeta can bind to membrane lipids and this binding may have detrimental effects on cell function. In this study, surface plasmon resonance technology was used to study Abeta binding to membranes.

Electrostatic and hydrophobic forces tether the proximal region of the angiotensin II receptor (AT1A) carboxyl terminus to anionic lipids.

The carboxyl terminus of the type-1 angiotensin II receptor (AT(1A)) is a focal point for receptor activation and deactivation. Synthetic peptides corresponding to the membrane-proximal, first 20 amino acids of the carboxyl terminus adopt an alpha-helical conformation in organic solvents, suggesting that the secondary structure of this region may be sensitive to hydrophobic environments. Using surface plasmon resonance, immobilized lipid chromatography, and circular dichroism, we examined whether this positively charged, amphipathic alpha-helical region of the AT(1A) receptor can interact with lipid components in the cell membrane and thereby modulate local receptor attachment and structure.