Purification of inclusion body—forming peptides and proteins in soluble form by fusion to Escherichia coli thermostable proteins

An expeditious and facile method of amyloid beta (1-42) purification

For the study of amyloid beta (Aβ) associated toxicity which is supposed to be the main pathological agent in Alzheimer's disease (AD), it is important to secure Aβ peptide with appropriate biological activity. However, commercial and synthetic Aβ often have some pitfalls like less cell toxicity, prompt aggregation and excess price, using recombinant technology, these issues can be resolved though the method also suffered from some problems such as low yield, aggregation and prolong time to purify. Thus, we previously developed an easy, economic and convenient method for Aβ42 purification using highly expressed GroES-Ubiquitin-Aβ42 fusion protein. The method was efficient, but further development was performed to improve the procedure and increase the yield. Focus was on the isolation of the fusion protein (GroES-Ubiquitin) from Aβ42 peptide. After a series of systematic testing with several chemicals, we found that methanol could precipitate efficiently the fusion protein, while the Aβ peptide was recovered in the supernatant. By this method, Aβ peptide was easily purified without tedious chromatographic steps which are main obstacles to purify the peptide in the previous method. This method yielded ~20 mg highly pure Aβ42 peptide from 1-liter bacterial culture. Different biophysical characterizations and bioactivity assays indicate that the peptide purified using this method was competitive with others which have been previously reported whereas considering the simplicity, final yield and time of purification, this method is the optimal solution.

Biophysical characterization as a tool to predict amyloidogenic and toxic properties of amyloid-β42 peptides

Amyloid-β42 (Aβ42) peptides are central to the amyloid pathology in Alzheimer's disease (AD). As biological mimetics, properties of synthetic Aβ peptides usually vary between vendors and batches, thus impacting the reproducibility of experimental studies. Here, we tested recombinantly expressed Aβ42 (Asp1 to Ala42) against synthetic Aβ42 from different suppliers using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), circular dichroism (CD) spectroscopy, thioflavin T aggregation, surface plasmon resonance and MTT cell viability assays. Overall, our recombinant Aβ42 provided a reproducible mimetic of desired properties. Across experimental approaches, the combined detection of Aβ42 dimers and random coil to β-sheet transition only correlated with aggregation-prone and cytotoxic peptides. Conclusively, combining MALDI-MS with CD appears to provide a rapid, reliable means to predict the "bioactivity" of Aβ42.

Evidence for a Strong Relationship between the Cytotoxicity and Intracellular Location of β-Amyloid

β-Amyloid (Aβ) is a hallmark peptide of Alzheimer’s disease (AD). Herein, we explored the mechanism underlying the cytotoxicity of this peptide. Double treatment with oligomeric 42-amino-acid Aβ (Aβ42) species, which are more cytotoxic than other conformers such as monomers and fibrils, resulted in increased cytotoxicity. Under this treatment condition, an increase in intracellular localization of the peptide was observed, which indicated that the peptide administered extracellularly entered the cells. The cell-permeable peptide TAT-tagged Aβ42 (tAβ42), which was newly prepared for the study and found to be highly cell-permeable and soluble, induced Aβ-specific lamin protein cleavage, caspase-3/7-like DEVDase activation, and high cytotoxicity (5–10-fold higher than that induced by the wild-type oligomeric preparations). Oligomeric species enrichment and double treatment were not necessary for enhancing the cytotoxicity and intracellular location of the fusion peptide. Taiwaniaflavone, an inhibitor of the cytotoxicity of wild-type Aβ42 and tAβ42, strongly blocked the internalization of the peptides into the cells. These data imply a strong relationship between the cytotoxicity and intracellular location of the Aβ peptide. Based on these results, we suggest that agents that can reduce the cell permeability of Aβ42 are potential AD therapeutics.

Data retrieved from in silico evaluation of vaccine potential of ZnuD protein in Acinetobacter baumannii

The nosocomial Acinetobacter baumannii is one of the most opportunistic pathogens that resists almost a broad range of antibiotics. Some bacterial metal acquisition systems are introduced as potential virulence factors in pathogen-host interaction.  Bacterial zinc uptake (Znu) systems are critical transporters that play a major role in the survival of the pathogen and the establishment of infections.  In silico characterization of ZnuD shows that it is an outer membrane protein with high conservancy rates in most Acinetobacter baumannii strains. The in silico derived physicochemical properties, structural and conserved immunoinformatic prediction data among Acinetobacter baumannii strains confirm that ZnuD belongs to Ton B dependent siderophore receptor families and is considered as a potential vaccine candidate. A more detailed interpretation of the data presented in this article is provided in "Identification and immunogenic properties of recombinant ZnuD protein loops of Acinetobacter baumannii" [1].

Emerging signal regulating potential of small molecule biflavonoids to combat neuropathological insults of Alzheimer's disease

Alzheimer's disease (AD) is a progressive, chronic and severe neurodegenerative disorder linked with cognitive and memory impairment that eventually lead to death. There are several processes which can cause AD, including mitochondrial dysfunction-mediated oxidative stress (OS), intracellular buildup of hyper-phosphorylated tau as neurofibrillary tangles (NFTs) and excessive buildup of extracellular amyloid beta (Aβ) plaques, and/or genetic as well as the environmental factors. Existing treatments can only provide symptomatic relief via providing temporary palliative therapy which can weaken the rate of AD-associated cognitive decline. Plants are the fundamental building blocks for the environment and produce various secondary metabolites. Biflavonoids are one among such secondary metabolite that possesses the potential to mediate noticeable change in the aggregation of tau, Aβ and also efficiently can decrease the toxic effects of Aβ oligomers in comparison with the monoflavonoid moieties. Nevertheless, the molecular processes remain to be exposed, flavonoids are found to cause a change in the Aβ and tau aggregation pathway to generate non-toxic aggregates. In this review, we discuss the neuroprotective action of small molecule biflavonoid to reduce the neurodegenerative events of AD. Furthermore, this appraisal advances our knowledge to develop potential new targets for the treatment of AD.

High Selectivity and Sensitivity of Oligomeric p-Phenylene Ethynylenes for Detecting Fibrillar and Prefibrillar Amyloid Protein Aggregates

Misfolding and aggregation of amyloid proteins into fibrillar aggregates is a central pathogenic event in neurodegenerative disorders such as Alzheimer's (AD) and Parkinson's diseases (PD). Currently, there is a lack of reliable sensors for detecting the range of protein aggregates involved in disease etiology, particularly the prefibrillar aggregate conformations that are more neurotoxic. In this study, the fluorescent sensing of two novel oligomeric p-phenylene ethynylenes (OPEs), anionic OPE1- and cationic OPE2+, for detecting prefibrillar and fibrillar aggregates of AD-associated amyloid-β (Aβ40 and Aβ42) and PD-associated α-synuclein proteins (wildtype, and single mutants A30P, E35K, and A53T) over their monomeric counterparts, were tested. Furthermore, the performance of OPEs was evaluated and compared to thioflavin T (ThT), the most widely used fibril dye. Our results show that OPE1- and OPE2+ exhibited aggregate-specific binding inducing large fluorescence turn-on and spectral shifts based on a combination of backbone planarization, hydrophobic unquenching, and superluminescent OPE complex formation sensing modes. OPEs exhibited higher selectivity, higher binding affinity, and comparable limits of detection for Aβ40 fibrils compared to ThT. OPE2+ exhibited the largest fluorescence turn-on and highest sensitivity. Significantly, OPEs detected prefibrillar aggregates of Aβ42 and α-synuclein that ThT failed to detect. The superior sensing performance, the nonprotein specific detection, and the ability to selectively detect fibrillar and prefibrillar amyloid protein aggregates point to the potential of OPEs to overcome the limitations of existing probes and promise significant advancement in the detection of the myriad of protein aggregates involved in the early stages of AD and PD.

Limited activation of the intrinsic apoptotic pathway plays a main role in amyloid-β-induced apoptosis without eliciting the activation of the extrinsic apoptotic pathway

Amyloid-β (Aβ), a main pathogenic factor of Alzheimer's disease (AD), induces apoptosis accompanied by caspase activation. However, limited caspase activation and the suppression of the intrinsic apoptotic pathway (IAPW) are frequently observed upon Aβ treatment. In this study, we investigated whether these suppressive effects of Aβ can be overcome; we also examined the death-related pathways. Single treatments of cells with Aβ42 for up to 48 h barely induced caspase activation. In cells treated with Aβ42 twice for 2 h followed by 22 h (2+22 h) or for longer durations, the apoptotic protease activating factor-1 (Apaf-1) apoptosome was formed and caspases-3 and -9 were activated to a certain extent, suggesting the activation of the IAPW. However, the Aβ42-induced activation of the IAPW differed from that induced by treatment with other agents, such as staurosporine (STS) in that lower amounts of cytochrome c were released from the mitochondria, the majority of procaspase-9 in the Apaf-1 complex was not processed and caspase-3 was activated to a lesser extent in the peptide-treated cells. Thus, it seemed that the IAPW was not fully activated by Aβ42. The 30- and 41/43-kDa fragments derived from procaspase-8 were detected, which appear to be produced through the IAPW without death-inducing signaling-complex (DISC) formation, a key feature of the extrinsic apoptotic pathway (EAPW). Bid cleavage was observed only after caspase-3 activity reached its maximal levels, suggesting that the cleavage may contribute in a limited capacity to the amplification process of the IAPW in the Aβ-treated cells. Taken together, our data suggest that the IAPW, albeit functional only to a limited extent, plays a major role in Aβ42-induced apoptosis without the EAPW.

Heterologous expression of Homo sapiens alpha-folate receptors in E. coli by fusion with a trigger factor for enhanced solubilization

The role of Alpha folate receptors (FRα) in folate metabolism and cancer development has been extensively studied. The reason for this is not only associated to its direct relation to disease development but also to its potential use as a highly sensitive and specific biomarker for cancers therapies. Over the recent years, the crystal structures of human FRα complexed with different ligands were described relying on an expensive and time-consuming production process. Here, we constructed an efficient system for the expression and purification of a human FRα in E. coli. Unlike a conventional expression method we used a specific protein fusion expressing the target protein together with a trigger factor (TF). This factor is a chaperone from E. coli that assists the correct folding of newly synthesized polypeptide chains. The activity of rTFFRα was comparable to glycosylphosphatidylinositol (GPI) anchored proteins extracted from HeLa tumor cells. Our work demonstrates a straightforward and versatile approach for the production of active human FRα by heterologous expression; this approach further enhances the development of inhibition studies and biotechnological applications. The purified product was then conjugated to liposomes, obtaining a 35% higher signal from densitometry measurement on the immunoblotting assay in the contruct containing the Ni-NTA tag, as a mimesis of an exosome, which is of vital importance to nanotherapeutic techniques associated to treatment and diagnosis of tumors.

Biflavonoids as Potential Small Molecule Therapeutics for Alzheimer's Disease

Flavonoids are naturally occurring phytochemicals found in a variety of fruits and vegetables and offer color, flavor, aroma, nutritional and health benefits. Flavonoids have been found to play a neuroprotective role by inhibiting and/or modifying the self-assembly of the amyloid-β (Aβ) peptide into oligomers and fibrils, which are linked to the pathogenesis of Alzheimer's disease. The neuroprotective efficacy of flavonoids has been found to strongly depend on their structure and functional groups. Flavonoids may exist in monomeric, as well as di-, tri-, tetra- or polymeric form through C-C or C-O-C linkages. It has been shown that flavonoids containing two or more units, e.g., biflavonoids, exert greater biological activity than their respective monoflavonoids. For instance, biflavonoids have the ability to distinctly alter Aβ aggregation and more effectively reduce the toxicity of Aβ oligomers compared to the monoflavonoid moieties. Although the molecular mechanisms remain to be elucidated, flavonoids have been shown to alter the Aβ aggregation pathway to yield non-toxic, unstructured Aβ aggregates, as well as directly exerting a neuroprotective effect to cells. In this chapter, we review biflavonoid-mediated Aβ aggregation and toxicity, and highlight the beneficial roles biflavonoids can potentially play in the prevention and treatment of Alzheimer's disease.

MBD4 interacts with and recruits USP7 to heterochromatic foci

MBD4 is the only methyl‐CpG binding protein that possesses a C‐terminal glycosylase domain. It has been associated with a number of nuclear pathways including DNA repair, DNA damage response, the initiation of apoptosis, transcriptional repression, and DNA demethylation. However, the precise contribution of MBD4 to these processes in development and relevant diseases remains elusive. We identified UHRF1 and USP7 as two new interaction partners for MBD4. Both UHRF1, a E3 ubiquitin ligase, and USP7, a de‐ubiquinating enzyme, regulate the stability of the DNA maintenance methyltransferase, Dnmt1. The ability of MBD4 to directly interact with and recruit USP7 to chromocenters implicates it as an additional factor that can potentially regulate Dnmt1 activity during cell proliferation. J. Cell. Biochem. 116: 476–485, 2015. © 2014 The Authors. Journal of Cellular Biochemistry published by Wiley Periodicals, Inc.

A novel method for expression and purification of authentic amyloid-β with and without (15)N labels

Amyloid-β (Aβ) is a major constituent in the senile plaques of patients with Alzheimer's disease (AD). Aβ has been intensively studied in amyloid research; however, challenges posed by data reproducibility arise from purity of synthetic Aβ and high expense for its isotope-labeling. The difficulties motivate development and optimization of recombinant Aβ (rAβ) production. Here, we report a new procedure to express and purify high quality rAβ40 from Escherichia coli. The new Aβ construct expressed insoluble Aβ fused with an N-terminal histidine-tag connected by a linker harboring TEV protease cut site. After purification and partial refolding, the fusion tag was removed by TEV protease cleavage, immobilized metal affinity chromatography (IMAC), and reversed phase-HPLC purification with a yield of 3.5 mg/L culture with and without (15)N label. The rAβ adopts classic amyloid fibrillization and is capable of binding to its clinical relevant metal ions.

Membrane-mediated neuroprotection by curcumin from amyloid-β-peptide-induced toxicity

Amyloid-β peptide (Aβ)-membrane interactions have been implicated in the formation of toxic oligomers that permeabilize membranes, allowing an influx of calcium ions and triggering cell death in the pathogenesis of Alzheimer's disease (AD). Curcumin, a small dietary polyphenolic molecule, has been shown to reduce Aβ-induced toxicity and AD pathology. We investigate here the effect of curcumin on Aβ40-induced toxicity in cultured human neuroblastoma SH-SY5Y cells and test a novel neuroprotection mechanism in which curcumin reduces Aβ-membrane interactions and attenuates Aβ-induced membrane disruptions. Predominantly monomeric Aβ40 exerts toxicity toward SH-SY5Y cells and has been shown to insert spontaneously into anionic lipid monolayers at the air/water interface, resulting in the misfolding and assembly of Aβ into β-sheet-enriched oligomers. Concomitantly, membrane morphology and lipid packing are disrupted. Curcumin dose-dependently ameliorates Aβ-induced neurotoxicity and reduces either the rate or extent of Aβ insertion into anionic lipid monolayers. Moreover, curcumin reduces Aβ-induced dye leakage from lipid-bilayer-covered, dye-loaded, porous silica microspheres. Because curcumin neither affects the inherent surface activity of Aβ nor modifies the membrane properties, it reduces Aβ insertion by directly attenuating Aβ-membrane interactions and reducing Aβ-induced membrane disruption. Although the exact molecular mechanism of curcumin's membrane protective effect remains unclear, this effect could in part contribute to curcumin's neuroprotective effect with respect to Aβ-induced toxicity. Our work reveals a novel molecular mechanism by which curcumin reduces Aβ-related pathology and toxicity and suggests a therapeutic strategy for preventing or treating AD by targeting the inhibition of Aβ-induced membrane disruption.

The inhibitory effects of Escherichia coli maltose binding protein on β-amyloid aggregation and cytotoxicity

The aggregation of β-amyloid (Aβ) peptide from its monomeric to its fibrillar form importantly contributes to the development of Alzheimer's disease. Here, we investigated the effects of Escherichia coli maltose binding protein (MBP), which has been previously used as a fusion protein, on Aβ42 fibrillization, in order to improve understanding of the self-assembly process and the cytotoxic mechanism of Aβ42. MBP, at a sub-stoichiometric ratio with respect to Aβ42, was found to have chaperone-like inhibitory effects on β-sheet fibril formation, due to the accumulation of Aβ42 aggregates by sequestration of active Aβ42 species as Aβ42-MBP complexes. Furthermore, MBP increased the lag time of Aβ42 polymerization, decreased the growth rate of fibril extension, and suppressed Aβ42 mediated toxicity in human neuroblastoma SH-SY5Y cells. It appears that MBP decreases the active concentration of Aβ42 by sequestering it as Aβ42-MBP complex, and that this sequestration suppresses ongoing nucleation and retards the growth rate of Aβ42 species required for fibril formation. We speculate that inhibition of the growth rate of potent Aβ42 species by MBP suppresses Aβ42-mediated toxicity in SH-SY5Y cells.

Vitellogenin recognizes cell damage through membrane binding and shields living cells from reactive oxygen species

Large lipid transfer proteins are involved in lipid transportation and diverse other molecular processes. These serum proteins include vitellogenins, which are egg yolk precursors and pathogen pattern recognition receptors, and apolipoprotein B, which is an anti-inflammatory cholesterol carrier. In the honey bee, vitellogenin acts as an antioxidant, and elevated vitellogenin titer is linked to prolonged life span in this animal. Here, we show that vitellogenin has cell and membrane binding activity and that it binds preferentially to dead and damaged cells. Vitellogenin binds directly to phosphatidylcholine liposomes and with higher affinity to liposomes containing phosphatidylserine, a lipid of the inner leaflet of cell membranes that is exposed in damaged cells. Vitellogenin binding to live cells, furthermore, improves cell oxidative stress tolerance. This study can shed more light on why large lipid transfer proteins have a well conserved α-helical domain, because we locate the lipid bilayer-binding ability of vitellogenin largely to this region. We suggest that recognition of cell damage and oxidation shield properties are two mechanisms that allow vitellogenin to extend honey bee life span.

Cloning, overexpression and biocatalytic exploration of a novel Baeyer-Villiger monooxygenase from Aspergillus fumigatus Af293

The presence of several putative Baeyer-Villiger Monooxygenases (BVMOs) encoding genes in Aspergillus fumigatus Af293 was demonstrated for the first time. One of the identified BVMO-encoding genes was cloned and successfully overexpressed fused to the cofactor regenerating enzyme phosphite dehydrogenase (PTDH). The enzyme named BVMOAf1 was extensively characterized in terms of its substrate scope and essential kinetic features. It showed high chemo-, regio- and stereoselectivity not only in the oxidation of asymmetric sulfides, (S)-sulfoxides were obtained with 99% ee, but also in the kinetic resolution of bicyclo[3.2.0]hept-2-en-6-one. This kinetic resolution process led to the production of (1S,5R) normal lactone and (1R,5S) abnormal lactone with a regioisomeric ratio of 1:1 and 99% ee each. Besides, different reaction conditions, such as pH, temperature and the presence of organic solvents, have been tested, revealing that BVMOAf1 is a relatively robust biocatalyst.

Cloning and characterization of ribulose-1,5-bisphosphate carboxylase/oxygenase small subunit (RbcS) cDNA from green microalga Ankistrodesmus convolutus

An initial study on gene cloning and characterization of unicellular green microalga Ankistrodesmus convolutus was carried out to isolate and characterize the full-length cDNA of ribulose-1,5-bisphosphate carboxylase/oxygenase small subunit (RbcS) as a first step towards elucidating the structure of A. convolutus RbcS gene. The full-length of A. convolutus RbcS cDNA (AcRbcS) contained 28 bp of 5' untranslated region (UTR), 225 bp of 3' non-coding region, and an open reading frame of 165 amino acids consisting of a chloroplast transit peptide with 24 amino acids and a mature protein of 141 amino acids. The amino acid sequence has high identity to those of other green algae RbcS genes. The AcRbcS contained a few conserved domains including protein kinase C phosphorylation site, tyrosine kinase phosphorylation site and N-myristoylation sites. The AcRbcS was successfully expressed in Escherichia coli and a ~21 kDa of anticipated protein band was observed on SDS-PAGE. From the phylogenetic analysis of RbcS protein sequences, it was found that the RbcS of A. convolutus has closer genetic relationship with green microalgae species compared to those of green seaweed and green macroalgae species. Southern hybridization analysis revealed that the AcRbcS is a member of a small multigene family comprising of two to six members in A. convolutus genome. Under different illumination conditions, RT-PCR analysis showed that AcRbcS transcription was reduced in the dark, and drastically recovered in the light condition. Results presented in this paper established a good foundation for further study on the photosynthetic process of A. convolutus and other green algae species where little information is known on Rubisco small subunit.

The recombinant amyloid-beta peptide Abeta1-42 aggregates faster and is more neurotoxic than synthetic Abeta1-42

Aggregation of the amyloid-beta (Abeta) peptide is considered a central event in the pathogenesis of Alzheimer's disease (AD). In order to bypass methodological bias related to a variety of impurities commonly present in typical preparations of synthetic Abeta, we developed a simple, generally applicable method for recombinant production of human Abeta and Abeta variants in Escherichia coli that provides milligram quantities of Abeta in very high purity and yield. Amyloid fibril formation in vitro by human Abeta1-42, the key amyloidogenic Abeta species in AD, was completed threefold faster with recombinant Abeta1-42 compared to synthetic preparations. In addition, recombinant Abeta1-42 was significantly more toxic to cultured rat primary cortical neurons, and it was more toxic in vivo, as shown by strongly increased induction of abnormal phosphorylation of tau and tau aggregation into neurofibrillary tangles in brains of P301L tau transgenic mice. We conclude that even small amounts of impurities in synthetic Abeta-including a significant fraction of racemized peptides that cannot be avoided due to the technical limitations of peptide synthesis--prevent or slow Abeta incorporation into the regular quaternary structure of growing beta-amyloid fibrils. The results validate the use of recombinant Abeta1-42 for both in vitro and in vivo studies addressing the mechanisms underlying Abeta aggregation and its related biological consequences for the pathophysiology, therapy, and prevention of AD.

Alternaria alternata TCTP, a novel cross-reactive ascomycete allergen

Defining more comprehensively the allergen repertoire of the ascomycete Alternaria alternata is undoubtedly of immense medical significance since this mold represents one of the most important, worldwide occurring fungal species responsible for IgE-mediated hypersensitivity reactions ranging from rhinitis and ocular symptoms to severe involvement of the lower respiratory tract including asthma with its life-threatening complications. Performing a hybridization screening of an excised A. alternata cDNA library with a radioactively labeled Cladosporium herbarum TCTP probe, we were able to identify, clone and purify the respective A. alternata homologue of TCTP which again represents a multifunctional protein that has been evolutionarily conserved from unicellular eukaryotes like yeasts to humans and appears, summarizing current literature, to be involved in housekeeping processes such as cell growth as well as cell-cycle progression, the protection of cells against various stress conditions including for instance apoptosis, and in higher organisms even in the allergic response. In this context, our present study characterizes recombinant A. alternata TCTP as a novel minor allergen candidate that displays a prevalence of IgE reactivity of approximately 4% and interestingly shares common, cross-reactive IgE epitopes with its C. herbarum and human counterparts as determined via Western blotting and in vitro inhibition approaches.

Recombinant amyloid beta-peptide production by coexpression with an affibody ligand

Background

Oligomeric and fibrillar aggregates of the amyloid β-peptide (Aβ) have been implicated in the pathogenesis of Alzheimer's disease (AD). The characterization of Aβ assemblies is essential for the elucidation of the mechanisms of Aβ neurotoxicity, but requires large quantities of pure peptide. Here we describe a novel approach to the recombinant production of Aβ. The method is based on the coexpression of the affibody protein Z_Aβ3, a selected affinity ligand derived from the Z domain three-helix bundle scaffold. Z_Aβ3 binds to the amyloidogenic central and C-terminal part of Aβ with nanomolar affinity and consequently inhibits aggregation.

Results

Coexpression of Z_Aβ3 affords the overexpression of both major Aβ isoforms, Aβ(1–40) and Aβ(1–42), yielding 4 or 3 mg, respectively, of pure ¹⁵N-labeled peptide per liter of culture. The method does not rely on a protein-fusion or -tag and thus does not require a cleavage reaction. The purified peptides were characterized by NMR, circular dichroism, SDS-PAGE and size exclusion chromatography, and their aggregation propensities were assessed by thioflavin T fluorescence and electron microscopy. The data coincide with those reported previously for monomeric, largely unstructured Aβ. Z_Aβ3 coexpression moreover permits the recombinant production of Aβ(1–42) carrying the Arctic (E22G) mutation, which causes early onset familial AD. Aβ(1–42)E22G is obtained in predominantly monomeric form and suitable, e.g., for NMR studies.

Conclusion

The coexpression of an engineered aggregation-inhibiting binding protein offers a novel route to the recombinant production of amyloidogenic Aβ peptides that can be advantageously employed to study the molecular basis of AD. The presented expression system is the first for which expression and purification of the aggregation-prone Arctic variant (E22G) of Aβ(1–42) is reported.