Human Aβ1-40(Amyloid Beta 1-40) ELISA Kit (E-EL-H0542)

Q1:What is the difference between (Aβ1-40) and (Aβ1-42)?

In mammals, the APP gene is located on chromosome 21 and has a total of 8 subtypes, whose subtypes generally contain 365~770 amino acid residues. The most common are APP695, APP751, and APP770, of which APP695 is highly expressed in the central nervous system. APP is a type I transmembrane glycoprotein with a molecular weight of about 110~130 kDa, with a large extracellular (amino terminal) domain and a small cytoplasmic tail region (intracellular carboxyl terminal). APP is metabolized mainly through two pathways: amyloid (β) pathway and non-amyloid (α) pathway. The amyloid pathway is that APP is cleaved by β-secretase into sAPPβ and a C-terminal fragment containing 99 amino acids. The latter is further cleaved by γ-secreting enzymes into Aβ and ACID, and the Aβ generated by this pathway accounts for 90% to 95% of the total Aβ, including two types of Aβ1-40 and Aβ1-42, of which the content of Aβ1-40 is higher, but Aβ1-42 has A strong hydrophobic effect, its toxicity is greater, and it is easy to polymerization. These Aβ fragments accumulate in mitochondria, lysosomes, and the endoplasmic reticulum, causing these suborganelles to malfunction. In the non-starchy source pathway based on alpha secretase, the alpha secretase cuts APP into sAPP and a C-terminal fragment containing 83 amino acids, which is then cut by gamma secretase to produce P3 and ACID, but these small fragments are cleared by neurons. The mutation of APP gene can cause abnormal protein expression or hydrolysis change, thus affecting the content and composition of Aβ in cells. Aβ mainly exists in the brain in the form of Aβ40 and Aβ42, and the content of Aβ42 is low (< 10%), but easy to aggregate, and then fibrosis and deposition, thus forming a diffuse senile plaque, which is also one of the main pathological characteristics of AD. Moreover, Aβ produced by APP after cleavage by β- and γ-secretory enzymes on the cell membrane can cause oxidative stress, calcium ion inflow, and then damage mitochondria, leading to nerve cell disorders, activation of apoptosis-related proteins and factors, and finally start the apoptosis process of cells. In addition, Aβ can also indirectly cause neuronal apoptosis by causing inflammation in the brain and neurofibrillary tangles, which is an important reason for the formation and development of AD.

Q2:Why is it necessary to add a protease inhibitor in tissue sample preparation during an Elisa experiment? Will it affect the detection significantly if there is no protease inhibitor?

Tissue samples may contain endogenous or exogenous proteases during processing, leading to degradation of extracted proteins. Therefore, it's necessary to add protease inhibitors during processing to ensure the integrity of target proteins. If customers can keep samples cold and handle them quickly during processing, omitting the protease inhibitor may not have a significant effect. After preparation, samples should be tested promptly or immediately aliquoted and frozen at -20°C or -80°C.

Q3:Which variant of the spike protein does this kit detect? Do you have a kit specific to detect the spike protein for the omicron variant?

This kit is designed for the original strain of the new crown virus, and the omicron variant has not been verified. However, we have verified 26 recombinant variants of the SARS-CoV-2 spike protein through the kit. For more information, customers can refer to the kit instructions (https://file.elabscience.com/Manual/covid_19/E-EL-E605 .pdf).

Q4:What is the range of enzyme activity of your IL-2 freeze-dried powder

Currently our freeze-dried powder is a concentration unit with no information on the activity unit for the time being.

Q5:What is the principle of adding stop solution to stop color reaction in ELISA experiment?

On the one hand, the activity of HRP enzyme is destroyed and the catalytic function of HRP enzyme is lost. On the other hand, the final color changes due to a change in pH.

Q6:The absorbance of the cell supernatant is less than that of the sample diluent alone, so how to concentrate the sample?

The amount of medium can be reduced for subsequent drug administration and modeling.

Q7:My sample volume is small. Can I reduce some reagents proportionally?

No, the detection system of our kits requires strict adherence to the specified sample volume to ensure accurate detection. If the sample volume is insufficient, consider diluting appropriately, but first conduct a pre-experiment to confirm the suitable dilution factor.

Q8:May I ask which type of plate to choose when ELISA testing?

According to the different bottom, it is divided into flat bottom, U-shaped bottom, V-shaped bottom and so on. The index of refraction of the flat bottom is low, which is suitable for detection in the enzyme reader. According to the color can be divided into transparent, black, white. Transparent is commonly used for the most general enzyme-linked immunoassay.

Q9:Is the TGF-β1 ELISA Kit detecting the active form of TGF-β1 or the precursor?

The active TGF-β dimer was detected

Q10:I need to measure corticosterone and testosterone in hair samples. Are there any suggested sample extraction methods?

Hair sample preparation method: Wash hair samples with methanol by adding 5 mL of HPLC-grade methanol to each sample, rotating for 3 minutes, then decanting excess methanol and rinsing hair twice. After washing, place the hair samples on aluminum foil, dry for 3 days in a protective cap. Weigh the dried hair samples and transfer them to 2ml polypropylene tubes containing stainless steel grinding beads. Place the tubes containing hair and beads in a bead beater, grind each sample for 2 minutes to produce powder. After grinding, add 1.5 mL of methanol to the tubes containing hair powder. Rotate samples slowly for 24 hours to extract steroids. Centrifuge at 10000 g for 4 minutes, transfer 0.6 mL of methanol supernatant containing steroids to new 1.5 mL microcentrifuge tubes. Dry the samples in a protective hood for 2-3 days to evaporate the methanol. Dilute the dried extract with 0.4 mL dilution buffer from the kit for detection.