1) We highly recommend storing the protein products as lyophilized powder and reconstituting the protein freshly. For the most of products, the lyophilized powder is more stable than liquid.

2) Please reconstitute the protein following the COA. Avoid repeated freeze-thaw cycles. The reconstituted protein must NOT be aliquoted to less than the minimum aliquoted amount on COA. If it is less than the minimum aliquoted amount on COA, we recommend users to add BSA or HSA for protection. Obviously, the user needs to make sure BSA or HSA doesn’t interfere with the assay they intend to run with the protein. This is critical to protect the protein against surface adsorption loss and inactivation.

3) It is recommended to store at the reconstituted concentration. If the used concentration is lower than the recommended reconstituted concentration, the customer can dilute the reconstituted protein before use; If the used concentration is higher than the recommended reconstituted concentration, the customer should be reconstituted it following the COA first, and then concentrate it to the required concentration.

We strongly suggest NOT to store the reconstituted product at 4 degree or at RT. If you need to use the protein multiple times during a period of time, the best way is to make single use aliquots, store them at -70℃ or below, and thaw the froze vials as needed. We do know one freeze-thaw cycle will not affect its activity.

Please note that the solubility of the protein is influenced by other factors in the formulation (before lyophilization) as well including trehalose. Normally, the maximal concentration we can obtain is the concentration of the bulk solution before lyophilization. If the customers really must make a higher reconstitution concentration than what recommended in the COA, it is suggested to reconstitute the product with concentration no higher than the concentration of the bulk solution before lyophilization.

1) Trehalose helps a lot to stabilize the protein solution and avoid any possible aggregation and precipitation, so we strongly recommend not to remove it, especially at higher protein concentration. In addition, trehalose will not interfere with primary amines or thiol related chemical reactions. If you really must use this protein without trehalose, for example used as analyte in SPR assays, we suggest you to run buffer exchange to get rid of trehalose immediate before use. There are many commercially available kits for this, such as Vivaspin ultrafiltration system. The products will be supplied in lyophilized form.

2)The bulk solution before lyophilization contains 10% trehalose as protectant. The trehalose concentration after recommended reconstitution varies from product to product and from lot to lot. But all relevant information will be provided to you on the lot-specific COA.

Trehalose is strongly recommended to avoid protein activity loss during handling and storage. If you really must use this protein without trehalose, we suggest to run buffer exchange to get rid of trehalose immediate before use. There are many commercially available kits for this, such as Vivaspin ultrafiltration system.

The shelf life (based on the storage conditions indicated) published on the COA is from the date the customer actually received the product.

From the formulation part of lot-specific COA, we could know the volume of the bulk solution before lyophilization. Concentration=Size(ug/mg)/Volume(ul)

All Fc-fused proteins will undergo Fc-mediated dimerization in solution. Some Fc-fusion proteins, depending on the structure of the protein itself, may further aggregate and form large polymers. The MW of the resulting protein species (dimer/trimer/polymer) may be reflected by the size of the band on a non-reducing SDS gel or SEC.

The endotoxin level of the bulk solution can represent the endotoxin level of the lyophilization product. According to experience, the endotoxin detection value of the lyophilization product is 20-30% higher than that of the bulk solution (within the normal range, because the amount needs to be increased and the purity factor needs to be considered during lyophilization). Our freeze-drying process is strictly sterile and without heat source. So the endotoxin level of the bulk solution can basically represent the endotoxin level of the lyophilization product.

Most of the products of our company do not add carrier protein, and only a few products add BSA. It is suggested to refer to the buffer information on the product website.

Most biotinylated proteins from ACRO biosystems are built upon Avi tag single point site-specific biotinylating. In theory, adding any molecules/tags could potentially affect the natural state of the protein, and consequently its bioactivity. However, the biotin molecule and the Avi tag are both small, and inserted outside the target protein domain. Also, the DoL (Degree of labeling) is optimized for specific protein at ACRO biosystems to achieve highest detection sensitivity without compromise bioactivity. Therefore, it’s very unlikely that the normal protein activity will be affected by the labeling event. The bioactivity of all labeled proteins will be tested the binding to antibody or ligand by ELISA, FACS or cell-based assays.

Biotinylated products are desalinated to remove the free biotin, and if there is any residual biotin, it is only a small amount.

The trehalose used by ACRO is injection grade and will be diluted during the experiment. In this case, trehalose should have no effect on the cells. We suggest that the buffer control group can be set up experimentally.

HEK293 cells also known as human embryonic kidney cells 293. The folding modification of HEK293 protein is closer to the form of real protein in human body. The folding modification of the protein expressed by HEK293 is closer to the form of real protein in human body, and most of the proteins we developed are targets or factors of human related diseases, so we chose HEK293 expression system

Integrins are obligate heterodimers (alpha and beta chain), and the transmembrane helixes mediate the dimerization of alpha and beta chain. As the integrin product we developed is the extracellular domain, we need to introduce the Acidic/Basic tails to stabilize the heterodimers. It can promote the form of heterodimer to ensure forming the correct structure of integrin, which will not have bad effect on the protein activity.

We usually use IMAC (Immobilized Metal-ion affinity chromatography) to purify the His tagged proteins to high purity. The IMAC beads we used for production are from GE, Qiagen and other vendors.