Neurodegeneration Reagents: Amyloid-Beta, Tau, Synuclein and What to Order

Our neurodegeneration listings rest on three systems of protein aggregation: amyloid-beta, tau and alpha-synuclein. Around those sit the trophic factors of the nervous system, markers of synaptic integrity, and the reagents for studying how the precursor proteins are processed. Gathered on the Alzheimer's topic page are the corresponding peptide standards, antisera, tracers carrying labels, and kits built on immunoassay. Below, the families are mapped, the reagent formats are matched to the questions they suit, and the reason these particular peptides demand more care at the bench than anything else we list is spelled out.

What the Alzheimer's topic covers

Anything whose parent molecule aggregates, arises as an intermediate during processing, marks neurons or synapses, or supports neuronal survival in a degeneration model belongs under this heading. In practice that spans APP and the enzymes that cut it, the diseases defined by tau, those defined by synuclein, prion work — which supplied the original model of one misfolded molecule templating the next — and the growth factors used to score whether neurons live. Because interneuron markers like somatostatin and galanin are measured routinely in these models, there is heavy overlap with our section on neuropeptides. Nothing listed is intended for anything beyond in-vitro assays and approved animal studies.

Amyloid-beta and the APP pathway

• Amyloid-beta — the family at the centre: Aβ(1–40), Aβ(1–42), Aβ(1–43), the reversed Aβ(42–1) control, truncated and pyroglutamated forms, and fluorescently labeled versions. Because Aβ42 aggregates far more readily than Aβ40, the two can never substitute for one another in an aggregation assay.
• Aβ40 S26C — a variant with a cysteine substitution, used to make covalently stabilised dimers and one of the standard means of separating oligomer effects from fibril effects.
• APLP — the amyloid precursor-like proteins, APP family members used to test whether an observation is specific to APP.
• AICD — the intracellular domain of APP liberated by gamma-secretase, studied as a signalling fragment in its own right.
• Presenilin — gamma-secretase's catalytic core; peptide reagents here support work on cleavage sites and inhibitors.
• SORL1 (SorLA) — a trafficking receptor for APP and a confirmed Alzheimer's risk gene, ordered increasingly often as the genetics literature expands.

Tau, synuclein and prion families

• Tau — full-length isoforms, the repeat-domain fragments making up the fibril core, and phosphopeptide standards matching the diagnostic phospho-epitopes. Since phospho-site specificity is the entire point of most tau antisera, the epitope specification matters more than the family name does.
• Alpha-synuclein — monomer standards, familial mutant sequences and the NAC-region fragments used in aggregation studies; central to Parkinson's and Lewy-body models as well as to mixed pathology.
• Prion protein — PrP fragments including the neurotoxic PrP(106–126) peptide, serving both prion research and the general mechanistic template for templated protein misfolding.
• CHIP — the co-chaperone ubiquitin ligase that routes misfolded tau and synuclein toward degradation; a proteostasis reagent rather than an aggregation species.

Neurotrophic, synaptic and neuroprotective families

• BDNF and NGF — our two best-selling neurotrophins, added to primary cultures to keep neurons alive and measured in model tissue as indices of plasticity.
• Neurotrophin family — NT-3 together with NT-4/5, plus the unprocessed pro-forms, which signal through p75 in the opposite direction and raise a question in their own right.
• CNTF — the ciliary neurotrophic factor, parent to a number of engineered fragments intended to protect neurons.
• Neurogranin — sitting postsynaptically and binding calmodulin, it ranks among the more solid CSF indicators that synapses are being lost.
• Humanin — the first member of the mitochondrial peptide group, originally pulled out of a screen looking for molecules that shield cells from Aβ toxicity.
• Nogo — myelin's brake on neurite extension, ordered for work on regeneration and on plasticity.
• Somatostatin and galanin — bought as stains for immunohistochemistry, since these interneuron populations shift dependably in model tissue.

Formats available under this topic

Synthetic standards supply the aggregating species themselves, and alongside them sit blocking peptides and calibrators bearing defined phosphate groups. Tagged material is in constant demand — Aβ carrying a fluorophore for watching uptake and clearance under the microscope, or a biotin handle when binding partners must be captured. Detection rests largely on polyclonal antisera, where what defines a reagent is which epitope it sees and whether it discriminates phosphorylation: something raised against every tau isoform is answering a quite different question from a pT181 reagent. Kits based on ELISA put numbers on Aβ40 and Aβ42, on tau both total and phosphorylated, and on neurogranin, in spinal fluid, plasma or homogenised brain; convention reports the ratio between the two Aβ species instead of either figure by itself. Aggregates are pulled down using magnetic beads, and epitopes across tau and synuclein are mapped with peptide libraries.

Choosing within a family

Start from the state of aggregation, because that is the experiment. One sequence will behave three ways as monomer, as oligomer and as fibril, and nothing in any catalogue arrives as a stable "oligomer" — that species has to be produced from monomer by a stated protocol. Buy monomer whose characterisation you trust and make what the design needs. Next comes the variant of the sequence itself: 40 residues or 42, a pyroglutamate at the front or an intact N-terminus, synuclein wild-type or bearing a familial mutation. With antisera, the third consideration is which epitope is recognised — phosphorylation site, structure-dependent or sequence-dependent binding, and the species validated. Last: to measure how much is present in a sample, a kit already validated beats assembling parts, both for speed and for reproducibility, whereas peptide alongside a raised antiserum is the route to localisation and mechanism.

Handling notes

Nothing else in this catalogue is as sensitive to handling as amyloid-beta, and most irreproducibility in the literature comes down to preparation rather than biology. Standard practice is to disaggregate the lyophilised peptide in hexafluoroisopropanol, evaporate it to a film, store that film desiccated at −20 °C or below, then resuspend in DMSO immediately before use and dilute into buffer — do not put Aβ42 straight into aqueous buffer and expect monomer. Prepare it fresh, use it once, and record the protocol in your methods, because it determines the outcome. Tau and synuclein tolerate more but still aggregate across freeze–thaw cycles. General practice appears in the solubility guide, the storage guide, the guide to aliquoting and, for confirming content, the COA guide.

Where to go next

Browse the complete Alzheimer's topic, the brain hub, or our overview of amyloid-beta, tau and alpha-synuclein reagents. Adjacent guides cover the neuropeptide section and the antibodies type guide, which counts for more here than in most topics.