A survey of peptides with effective therapeutic potential in Alzheimer's disease rodent models or in human clinical studies.

Alzheimer's disease (AD) is a devastating neurodegenerative disorder and the most common cause of dementia. Today, only palliative therapies are available. The pathological hallmarks of AD are the presence of neurofibrillary tangles and amyloid plaques, mainly composed of the amyloid-β peptide (Aβ), in the brains of the patients.

Peptides for therapy and diagnosis of Alzheimer's disease.

Alzheimer's disease (AD) is a progressive neurodegenerative disorder with devastating effects. The greatest risk factor to develop AD is age. Today, only symptomatic therapies are available.

Fluorine-18 labeling of three novel D-peptides by conjugation with N-succinimidyl-4-[18F]fluorobenzoate and preliminary examination by postmortem whole-hemisphere human brain autoradiography.

Introduction: β-Amyloid (Aβ) plaques and neurofibrillary tangles are the main characteristics of Alzheimer's disease (AD). Positron emission tomography (PET), a high-resolution, sensitive, and noninvasive imaging technique, has been widely utilized in visualizing the localization of plaques and tangles and thereby distinguishing between AD and healthy controls. A small 12-mer D-enantiomeric peptide (amino acid sequence=QSHYRHISPAQV), denoted as D1, has high binding affinity to Aβ in vitro in the sub-micromolar range, and consequently, its radiolabeled analogues have a potential as radioligands for visualizing amyloid plaques in vivo by PET.

iHADAMAC: a complementary tool for sequential resonance assignment of globular and highly disordered proteins.

An experiment, iHADAMAC, is presented that yields information on the amino-acid type of individual residues in a protein by editing the (1)H-(15)N correlations into seven different 2D spectra, each corresponding to a different class of amino-acid types. Amino-acid type discrimination is realized via a Hadamard encoding scheme based on four different spin manipulations as recently introduced in the context of the sequential HADAMAC experiment. Both sequential and intra-residue HADAMAC experiments yield highly complementary information that greatly facilitate resonance assignment of proteins with high frequency degeneracy, as demonstrated here for a 188-residue intrinsically disordered protein fragment of the hepatitis C virus protein NS5A.

Distribution and binding of 18F-labeled and 125I-labeled analogues of ACI-80, a prospective molecular imaging biomarker of disease: a whole hemisphere post mortem autoradiography study in human brains obtained from Alzheimer's disease patients.

One of the major pathological landmarks of Alzheimer's disease and other neurodegenerative diseases is the presence of amyloid deposits in the brain. The early non-invasive visualization of amyloid is a major objective of recent diagnostic neuroimaging approaches, including positron emission tomography (PET), with an eye on follow-up of disease progression and/or therapy efficacy. The development of molecular imaging biomarkers with binding affinity to amyloid in the brain is therefore in the forefront of imaging biomarker and radiochemistry research.

Relaxation behavior study of ultrasmall superparamagnetic iron oxide nanoparticles at ultralow and ultrahigh magnetic fields.

Ultrasmall superparamagnetic iron oxide nanoparticles (USPIOs) have attracted attention because of their current and potential usefulness as contrast agents for magnetic resonance imaging (MRI) and nuclear magnetic resonance (NMR). USPIOs are usually used for their significant capacity to produce predominant proton relaxation effects, which result in signal reduction. However, most previous studies that utilized USPIOs have been focused on the relaxation behavior at commonly used magnetic fields of clinical MRI systems (typically 1-3 T).

Crystallization and preliminary X-ray crystallographic studies of an oligomeric species of a refolded C39 peptidase-like domain of the Escherichia coli ABC transporter haemolysin B.

The ABC transporter haemolysin B (HlyB) from Escherichia coli is part of a type I secretion system that translocates a 110 kDa toxin in one step across both membranes of this Gram-negative bacterium in an ATP-dependent manner. Sequence analysis indicates that HlyB contains a C39 peptidase-like domain at its N-terminus. C39 domains are thiol-dependent peptidases that cleave their substrates after a GG motif.

1H, 13C, and 15N resonance assignment of a 179 residue fragment of hepatitis C virus non-structural protein 5A.

Non-structural protein 5A (NS5A) plays an important role in the life cycle of hepatitis C virus. This proline-rich phosphoprotein is organized into three domains. Besides its role in virus replication and virus assembly, NS5A is involved in a variety of cellular regulation processes.

c-Src is required for complex formation between the hepatitis C virus-encoded proteins NS5A and NS5B: a prerequisite for replication.

Unlabelled: Hepatitis C virus (HCV) is a leading cause of chronic liver disease worldwide and establishes a persistent infection in more than 60% of infected individuals. This high frequency of persistent infection indicates that HCV has evolved efficient strategies to interfere with the adaptive and innate immune response and to occupy and use host cell infrastructure. The present study provides evidence that c-Src, a member of the Src family kinases that participates in many signal transduction pathways, represents an essential host factor exploited for viral replication.

In vitro conversion and seeded fibrillization of posttranslationally modified prion protein.

The conversion of the cellular isoform of the prion protein (PrP(C)) into the pathologic isoform (PrP(Sc)) is the key event in prion diseases. To study the conversion process, an in vitro system based on varying the concentration of low amounts of sodium dodecyl sulfate (SDS) has been employed. In the present study, the conversion of full-length PrP(C) isolated from Chinese hamster ovary cells (CHO-PrP(C)) was examined.

Structural insights into conformational changes of a cyclic nucleotide-binding domain in solution from Mesorhizobium loti K1 channel.

Cyclic nucleotide-sensitive ion channels, known as HCN and CNG channels, are activated by binding of ligands to a domain (CNBD) located on the cytoplasmic side of the channel. The underlying mechanisms are not well understood. To elucidate the gating mechanism, structures of both the ligand-free and -bound CNBD are required.

1H, 15N and 13C resonance assignment of the N-terminal C39 peptidase-like domain of the ABC transporter Haemolysin B (HlyB).

ATP-binding cassette (ABC) transporters are ubiquitous integral membrane proteins, which catalyze the translocation of molecules across biological membranes in an ATP-dependent manner. Despite the diversity in the transported substrates, they all share the same architecture, comprised of two transmembrane (TMD) and two nucleotide-binding domains (NBD). Members of the bacteriocin ABC transporter subfamily feature a special domain, belonging to the C39 (cystein protease family 39) peptidase protein family.

Sequence-independent control of peptide conformation in liposomal vaccines for targeting protein misfolding diseases.

Synthetic peptide immunogens that mimic the conformation of a target epitope of pathological relevance offer the possibility to precisely control the immune response specificity. Here, we performed conformational analyses using a panel of peptides in order to investigate the key parameters controlling their conformation upon integration into liposomal bilayers. These revealed that the peptide lipidation pattern, the lipid anchor chain length, and the liposome surface charge all significantly alter peptide conformation.

Molecular interactions between prions as seeds and recombinant prion proteins as substrates resemble the biological interspecies barrier in vitro.

Prion diseases like Creutzfeldt-Jakob disease in humans, Scrapie in sheep or bovine spongiform encephalopathy are fatal neurodegenerative diseases, which can be of sporadic, genetic, or infectious origin. Prion diseases are transmissible between different species, however, with a variable species barrier. The key event of prion amplification is the conversion of the cellular isoform of the prion protein (PrP(C)) into the pathogenic isoform (PrP(Sc)).

Oral treatment with the d-enantiomeric peptide D3 improves the pathology and behavior of Alzheimer's Disease transgenic mice.

Several lines of evidence suggest that the amyloid-β-peptide (Aβ) plays a central role in the pathogenesis of Alzheimer's disease (AD). Not only Aβ fibrils but also small soluble Aβ oligomers in particular are suspected to be the major toxic species responsible for disease development and progression. The present study reports on in vitro and in vivo properties of the Aβ targeting d-enantiomeric amino acid peptide D3.

Insights into the mechanism of ligand binding to octopine dehydrogenase from Pecten maximus by NMR and crystallography.

Octopine dehydrogenase (OcDH) from the adductor muscle of the great scallop, Pecten maximus, catalyzes the NADH dependent, reductive condensation of L-arginine and pyruvate to octopine, NAD(+), and water during escape swimming and/or subsequent recovery. The structure of OcDH was recently solved and a reaction mechanism was proposed which implied an ordered binding of NADH, L-arginine and finally pyruvate. Here, the order of substrate binding as well as the underlying conformational changes were investigated by NMR confirming the model derived from the crystal structures.

Nanodiscs allow the use of integral membrane proteins as analytes in surface plasmon resonance studies.

Nanodiscs are small-sized and flat model membranes that provide a close to native environment for reconstitution of integral membrane proteins. Incorporation of membrane proteins into nanodiscs results in water-soluble proteolipid particles making the membrane proteins amenable to a multitude of bioanalytical techniques originally developed for soluble proteins. The transmembrane domain of the human CD4 receptor was fused to ubiquitin with a preceding N-terminal decahistidine tag.

Assessment of GABARAP self-association by its diffusion properties.

Gamma-aminobutyric acid type A receptor-associated protein (GABARAP) belongs to a family of small ubiquitin-like adaptor proteins implicated in intracellular vesicle trafficking and autophagy. We have used diffusion-ordered nuclear magnetic resonance spectroscopy to study the temperature and concentration dependence of the diffusion properties of GABARAP. Our data suggest the presence of distinct conformational states and provide support for self-association of GABARAP molecules.

Resonance assignments of the nucleotide-free wildtype MloK1 cyclic nucleotide-binding domain.

Cyclic nucleotide-sensitive ion channels, known as HCN and CNG channels play crucial roles in neuronal excitability and signal transduction of sensory cells. These channels are activated by binding of cyclic nucleotides to their intracellular cyclic nucleotide-binding domain (CNBD). A comparison of the structures of wildtype ligand-free and ligand-bound CNBD is essential to elucidate the mechanism underlying nucleotide-dependent activation of CNBDs.

Single vector system for efficient N-myristoylation of recombinant proteins in E. coli.

Background: N-myristoylation is a crucial covalent modification of numerous eukaryotic and viral proteins that is catalyzed by N-myristoyltransferase (NMT). Prokaryotes are lacking endogenous NMT activity. Recombinant production of N-myristoylated proteins in E.

Solution structure of Atg8 reveals conformational polymorphism of the N-terminal domain.

During autophagy a crescent shaped like membrane is formed, which engulfs the material that is to be degraded. This membrane grows further until its edges fuse to form the double membrane covered autophagosome. Atg8 is a protein, which is required for this initial step of autophagy.

Competitively selected protein ligands pay their increase in specificity by a decrease in affinity.

Protein-ligand interactions characterise and govern the current state and fate of a living cell. The specificity of proteins is mainly determined by the relative affinities to each potential ligand. To investigate the consequences and potentials of ligands with increased specificity in comparison with ligands optimised solely for affinity, it was necessary to identify ligands that are optimised towards specificity instead of a barely optimised affinity to a given target.

Amyloid formation: age-related mechanism in Creutzfeldt-Jakob disease?

Protein aggregation occurs in many age-related neurodegenerative diseases, where it can lead to deposits of naturally occurring proteins in the brain. In case of Creutzfeldt-Jakob disease (CJD), these deposits consist of prion protein (PrP). CJD has three etiologies: spontaneous, genetic, or caused by infection.