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Clippingdale, Andrew B.; He, Weilan; Macris, Mary; Wade, John D.; Barrow, Colin J.

doi:10.1023/a:1008931309727

Cited by 4 publications

(6 citation statements)

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“…20 In addition, 2-hydroxy-4-methoxybenzyl backbone protection has been used, in part to aid in the HPLC peak shape and preparative yield of both Ab1-43 and Ab1-40. 14,21,22 The N-terminally truncated forms of Ab give lower yields and have poorer peak shape than full length Ab, probably due to their increased amyloidogenicity and poorer solubility. 10 In our hands, semipreparative HPLC using both Vydac C4 and Zorbax Stablebond C3, C8 and C18 columns at room temperature gave yields of less than 5% for both Ab3pE-40 and p3.…”

Section: Resultsmentioning

confidence: 99%

On-line high-performance liquid chromatography/mass spectrometric investigation of amyloid-β peptide variants found in Alzheimer's disease

Thompson

Lim

Barrow

1999

Rapid Commun. Mass Spectrom.

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Abeta peptides are the major components of amyloid deposits in Alzheimer's disease. The presence of N-terminally truncated Abeta variants in amyloid may be a critical factor in Alzheimer's disease pathogenesis. These Abeta variants are less soluble and more amyloidogenic than full-length Abeta, making their separation, purification and identification difficult. High-performance liquid chromatography (HPLC) at elevated temperatures, coupled to electrospray ionization (ES) mass spectrometry (MS), enables rapid separation and identification of N-terminally truncated Abeta variants. This methodology provides a potential tool for exploring the importance of these Abeta variants in both the pathogenesis and diagnosis of Alzheimer's disease.

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Section: Resultsmentioning

confidence: 99%

On-line high-performance liquid chromatography/mass spectrometric investigation of amyloid-β peptide variants found in Alzheimer's disease

Thompson

Lim

Barrow

1999

Rapid Commun. Mass Spectrom.

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“…While these techniques showed good sensitivity and selectivity, they also have some disadvantages such as needed complicated instrument and semi‐quantitative characteristics . Also, they need a long time for sample preparation and analysis that could results in some structural changes of Aβ due to the ionic strength, acidity, temperature, and other environmental conditions . In our previous work we have reported Raman spectroscopy as a powerful technique for monitoring Aβ peptide in a short time without any sample preparation, but the sensing device is also expensive .…”

Section: Introductionmentioning

confidence: 99%

Label‐free Electrochemical Sensor for Ex‐vivo Monitoring of Alzheimer's Disease Biomarker

et al. 2016

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1IntroductionAlzheimersd isease (AD) is an eurodegenerative disorder characterizedb ya ggregation of beta-amyloid (Ab) peptidea nd formation of neurofibrillary tangles in the neuronsa sw ell as oxidatived amage of lipids, protein, DNAa nd RNA [1][2][3].A Dc ould be diagnosed by using clinicala nalysis,b ut it could be misdiagnosed with some other neurological diseases.A b peptidew as used as the key marker in the early diagnosis of AD [4] based on several detection methods such as the use of amyloid-reactive dyes [5],b ut this method is disadvantagedb ecause the dye should cross the blood-brain barrier.I na ddition, enzyme-linked immunosorbent assay (ELISA),f luorescence,a nd scanning tunneling microscopy methods have been developedf or detection of Ab [6][7][8].W hile these techniques showed good sensitivity and selectivity,t hey also have some disadvantages such asneeded complicated instrument and semi-quantitativec haracteristics [9].A lso, they need along time for sample preparation and analysis that could results in somes tructuralc hanges of Ab due to the ionic strength, acidity, temperature,a nd other environmental conditions [10,11].I no ur previous work we have reported Ramans pectroscopy as ap owerful technique for monitoring Ab peptide in as hort time without any sample preparation, but the sensing device is also expensive [12].Thus,i ti sc ritically important to developafast sensor that could detect Ab concentrationi ni ts aggregate forming step which would be amore suitable candidate to predict AD.E lectrochemicalt echniques have been widely used in variousb iological fields such as clinicald iagnosis, biomedical research, food quality control and environmental monitoring due to its high sensitivity,s implicity, and rapid response. During the last decade few attempts have been reported to apply differente lectrochemical techniques for monitoring Ab peptides and their aggregated forms by usingv ariousm odified electrodes [13][14][15][16][17][18][19][20][21][22]. However, most of them were electrochemical immunosensor label-based systems for in-vitro detection;t hey also include immobilization of peptide into the electrode surface or the detection of the Ab in solutions such as Fe(CN) 6 3À that could change the peptide structure[ 21, 23] D-galactose (DG) is one of the reducing sugars that could be converted into glucose by galactose-1-phosphate uridyltransferase and galactokinase enzymes [24,25].B ut, at higher levels it will be accumulated in the cells and reacts with the free amines (in proteins and peptides) to form advancedg lycation end products [25] leadingt oo smotic stress and generation of reactiveo xygen species [26].D Gw as used for studying in-vivo AD [27][28][29][30],d ue to its ability to induce oxidative stress in cultured rat fetal brain neurons that may be contributed to the neurode-Abstract:T he beta-amyloid (Ab)p eptide was useda sa n important biomarker for Alzheimersd isease (AD) diagnosis.T he developmento fa na ccurate,s elective, rapid, and highly sensitive technique for detecti...

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“…These peptides often result in low yields and limited purities 2,4–6 . Some examples are the amyloid forming peptides like amyloid-β (Aβ) 2 , α-synuclein 7,8 , and acyl carrier protein (ACP) 65–74 9 , and some hydrophobic trans-membrane segments of proteins, like glycophorin A, epidermal growth factor (EGFR) and M2 ion channel 10 .…”

Section: Introductionmentioning

confidence: 99%

“…Some approaches specifically target the peptide backbone. These include photo-triggered interruption of amide bond formation with ester bonds (o-acyl isopeptide) 35–37 , introduction of pseudoproline, which acts as a β-sheet breaker to prevent aggregation during coupling 38 , and the use of other chemical moieties to act as backbone protecting intermediates 4,39–41 . Most of these techniques are useful in producing higher yields of hydrophobic peptides but are also, to varying degrees, cumbersome and expensive to undertake on a routine basis.…”

Section: Introductionmentioning

confidence: 99%

Improved chemical synthesis of hydrophobic Aβ peptides using addition of C‐terminal lysines later removed by carboxypeptidase B

2014

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Many amyloidogenic peptides are highly hydrophobic, introducing significant challenges to obtaining high quality peptides by chemical synthesis. For example, while good yield and purity can be obtained in the solid phase synthesis of the Alzheimer’s plaque peptide Aβ40, addition of a C-terminal Ile-Ala sequence to generate the more toxic Aβ42 molecule creates a much more difficult synthesis resulting in low yields and purities. We describe here a new method that significantly improves the Fmoc solid phase synthesis of Aβ peptides. In our method, Lys residues are linked to the desired peptide’s C-terminus through standard peptide bonds during the synthesis. These Lys residues are then removed post-purification using immobilized carboxypeptidase B. With this method we obtained both Aβ42 and Aβ46 of superior quality that, for Aβ42, rivals that obtained by recombinant expression. Intriguingly, the method appears to provide independent beneficial effects on both the total synthetic yield and on purification yield and final purity. Reversible Lys addition with carboxypeptidase B removal should be a generally useful method for making hydrophobic peptides that is applicable to any sequence not ending in Arg or Lys. As expected from the additional hydrophobicity of Aβ46, which is extended from the sequence Aβ42 by a C-terminal Thr-Val-Ile-Val sequence, this peptide makes typical amyloid at rates significantly faster than for Aβ42 or Aβ40. The enhanced amyloidogenicity of Aβ46 suggests that, even though it is present in relatively low amounts in the human brain, it could play a significant role in helping to initiate Aβ amyloid formation.

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Cited by 4 publications

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On-line high-performance liquid chromatography/mass spectrometric investigation of amyloid-β peptide variants found in Alzheimer's disease

On-line high-performance liquid chromatography/mass spectrometric investigation of amyloid-β peptide variants found in Alzheimer's disease

Label‐free Electrochemical Sensor for Ex‐vivo Monitoring of Alzheimer's Disease Biomarker

Improved chemical synthesis of hydrophobic Aβ peptides using addition of C‐terminal lysines later removed by carboxypeptidase B

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