StressMarq's neurodegenerative proteins (pre-formed fibrils (PFFs), oligomers and monomers**) are shipped frozen on dry ice. Neurodegenerative proteins going to destinations within the USA are shipped from our storage facility in the USA. This prevents potential delays at US Customs that could affect product quality. **NOTE: Amyloid Beta Monomers (catalog# SPR-485) do not require dry ice when ordered on their own. However, if ordered together with other neurodegenerative proteins, they are shipped on dry ice to save on shipping costs.

Please refer to the Handling Instructions for Neurodegenerative Proteins page for detailed instructions by protein and construct type.

Please refer to the Handling Instructions for Neurodegenerative Proteins page for detailed instructions by protein and construct type.  IMPORTANT: pre-formed fibrils (PFFs) should never be left on ice or at 4°C.

If you are not planning to use the product imminently, it is generally best to thaw and aliquot into suitable aliquots for your intended use, and then re-freeze. After aliquoting the first time, it is not recommended to aliquot a second time. Freeze-thaw cycles may decrease product activity. It is also not recommended to flash-freeze aliquots.

The purity of the neurodegenerative proteins is determined using SDS-PAGE after purification. A sedimentation assay is also performed on pre-formed fibrils (PFFs) to assess the amount of soluble protein present and determine how much of the monomer was converted to fibril.

We assess seeding activity for alpha synuclein and tau pre-formed fibrils (PFFs) via Thioflavin T (ThT) assay. For more information, please refer to the Alpha Synuclein ThT Assay Protocol and/or the Tau ThT Assay Protocol.

Alpha Synuclein and Tau PFFs: Purity is determined via SDS-PAGE. Sedimentation assays are performed on PFFs to ensure that most of the monomer was converted to fibril. Thioflavin T is used for seeding assays. Structure is confirmed by AFM (Atomic Force Microscopy) or TEM (Transmission Electron Microscopy). Endotoxin testing and sterility checks are also part of our standard QC procedures. Amyloid Beta Oligomers and PFFs: Western Blot with an amyloid beta antibody (6E10) is done to verify oligomer/fibrillar species. Structure is confirmed by AFM (Atomic Force Microscopy) or TEM (Transmission Electron Microscopy). Endotoxin testing and sterility checks are also part of our standard QC procedures.

We suggest reviewing our neurodegenerative proteins page to see the products offered by StressMarq. Additional information that may be helpful includes protocols, handling instructions and FAQs. If you'd like help choosing a product, please email techsupport@stressmarq.com. Include the details of your experimental conditions and goals, and we will do our best to recommend a sutiable product.

There are several types and models of sonicators (bath, probe, etc). Since each lab/researcher may have a different type or model of sonicator, we recommend referring to the information on our Sonication Protocol page. Researchers will always need to optimize their protocol for their particular experiment, lab, and sonicator.

Please refer to the Neurodegenerative Proteins Protocols page, which includes protocols for Thioflavin T (ThT), cell culture, in vivo procedures, and more.

The standard concentration for alpha synuclein and tau proteins is 2mg/mL. Standard concentration for amyloid beta proteins is 1mg/mL. Select alpha synuclein and tau proteins are also offered at a concentration of 5mg/mL (please refer to the ordering section on each product detail page). To calculate Molarity, use the molecular weight of the monomer and the following formula: μM = (μg/L) / (MW in Da) We use the molecular weight (MW) of the monomer, as it would be difficult to determine how many monomeric units go into each fibril and calculate their specific mass.

Yes, StressMarq neurodegenerative disease proteins are frequently cited in peer-reviewed scientific journal publications. Citations for a specific product can be found on that product's detail page under the "Product Citations" section. For example, see the citations for Alpha Synuclein Pre-formed Fibrils, catalog# SPR-322. A complete list of product citations for our neurodegenerative disease proteins can be found here: Product Citations for Neurodegenerative Disease Proteins Lastly, to see only the most recent citations for each neurodegenerative disease protein, refer to the alpha synuclein, tau, and amyloid beta overview pages.

Appropriate controls are dependant on the experiment being performed. Generally, it is recommended to use the starting monomer source as a control for the PFFs. For example, use catalog#SPR-321 (monomer) as a monomer control for catalog# SPR-322 (PFFs). Monomer source for each PFFs is listed on the product page under "Other Relevant Information". Beta synuclein PFFs can also be used as a control for alpha synuclein PFFs, since they do not seed aggregation.

Our human alpha synuclein PFFs (catalog# SPR-322) have been shown to induce pSer129 pathology in human iPSC neurons. Mouse alpha synuclein PFFs (catalog#SPR-324) do not appear to seed human monomers well in vitro by Thioflavin T assay, despite similar homology. According to the literature (Luk et al. 2016), cross-seeding between human and mouse alpha synuclein is less efficient than homologous seeding.

To prevent any spontaneous fibrillization, we recommend that monomeric protein be kept on ice during thawing and use. If any spontaneous fibrillization does occur, the amount that aggregates will be very small, since aggregation typically requires shaking/agitation.

Our human (catalog# SPR-322) and mouse (catalog# SPR-324) alpha synuclein PFFs seed endogenous alpha synuclein and have been successfully injected into mice and rats, inducing alpha synuclein pathology that spreads away from the injection site. Experimental data and images can be found on the product pages.

Type 1 and Type 2 alpha synuclein monomers are highly similar, differing by an additional N-terminal methionine in Type 2 and variations in expression and purification methods. These differences may contribute to distinct structural and functional properties of the resulting PFFs. Type 1 PFFs have been reported to exhibit higher β-sheet content, stronger seeding activity, greater fibril formation, and more robust pSer129 alpha synuclein pathology, whereas Type 2 PFFs tend to show lower aggregation, weaker seeding activity, and potentially slower pathology development, although they can still induce cellular toxicity and pathology under appropriate experimental conditions. Read our blog to learn more: Alpha Synuclein Type 1 and Type 2: What’s the Difference?

On a benchtop at room temperature, amyloid beta fibrils are quite stable through a freeze-thaw cycle and for weeks in their acidic buffer. Amyloid beta oligomers are stable through a freeze-thaw and maintain their size throughout size-exclusion chromatography.

Amyloid beta fibrils require sonication before experiments. Although they are soluble in their acidic buffer, the amyloid beta fibrils tend to aggregate when introduced to neutral buffers and become insoluble. In this case we recommend sonicating immediately prior to experimental use. Amyloid beta oligomers do not require sonication.

These are disordered proteins that exist in equilibrium. Unfortunately, monomers cannot be removed from oligomer and fibril preps because monomers aggregate readily on filters. Thus, there is likely still some monomer present in these preparations, however, the amount is difficult to quantify since SDS breaks down aggregates into monomers. The Western blot images on our website show the monomer, oligomer, and fibril preps run at the same concentration, and there is less than 5% of the monomer signal left in the oligomer and fibril preps, even in the presence of SDS (which breaks aggregates down into monomers).

Tau (K18) P301L Mutant PFFs (catalog # SPR-330) have been validated for inducing tau phosphorylation and aggregation in P301L mouse hippocampus nine weeks post-injection. More details on the experiments can be found on the product page.

Yes, we offer several hyper-phosphorylated tau monomers and fibrils expressed in Baculovirus/Sf9. Theese include: wild-type tau monomers (catalog# SPR-496) and PFFs (catalog#SPR-498), and tau P301S mutant monomers (catalog# SPR-473) and PFFs (catalog#SPR-471). Mass spectrometry analysis has shown up to 20 phosphorylated sites for Baculovirus-expressed wild-type tau, and 38 phosphorylated sites for the Baculovirus-expressed P301S mutant tau. Additionally, we offer tau P301S mutant monomers (catalog# SPR-515) and PFFs (catalog# SPR-516) expressed in CHO cells that are N-glycosylated and hyper-phosphorylated.