1) We strongly recommend storing protein products in their lyophilized form and reconstituting them freshly before use. For most products, the lyophilized powder is significantly more stable than the liquid form.

2) Please follow the instructions on the Certificate of Analysis (COA) when reconstituting the protein. Avoid repeated freeze–thaw cycles. The reconstituted protein must not be aliquoted into portions smaller than the minimum aliquot size indicated on the COA.If smaller aliquots are required, we recommend adding BSA or HSA as a stabilizer, provided they do not interfere with your intended assay. This step is important to minimize protein loss from surface adsorption and prevent inactivation.

3) It is recommended to store the protein at the reconstituted concentration.

* If a lower working concentration is needed, dilute the reconstituted protein immediately before use.

* If a higher concentration is required, first reconstitute the protein according to the COA, then concentrate it to the desired level.

We strongly recommend not storing the reconstituted product at 4°C or room temperature. If the protein will be used multiple times over a period, the best approach is to prepare single-use aliquots, store them at –70°C or below, and thaw individual vials as needed. One freeze–thaw cycle is not expected to affect the protein’s activity.

Please note that the protein’s solubility can be influenced by formulation components present before lyophilization, such as trehalose. In general, the maximum achievable concentration corresponds to that of the bulk solution prior to lyophilization. If customers need to prepare a higher concentration than that recommended on the COA, it is advised not to exceed the concentration of the bulk solution before lyophilization when reconstituting the product.

1) Trehalose plays a critical role in stabilizing the protein solution and preventing aggregation or precipitation, especially at higher protein concentrations. We strongly recommend not removing it. Trehalose does not interfere with reactions involving primary amines or thiols. If you need to use the protein without trehalose—for example, as an analyte in SPR assays—we suggest performing a buffer exchange immediately before use. Commercially available kits, such as the Vivaspin ultrafiltration system, can be used for this purpose. All products are supplied in lyophilized form.

2) The bulk solution before lyophilization contains 10% trehalose as a stabilizing agent. After reconstitution, the trehalose concentration may vary depending on the product and lot. Detailed information is provided on the lot-specific COA.

Trehalose is strongly recommended to preserve protein activity during handling and storage. If it is necessary to use the protein without trehalose, we suggest performing a buffer exchange immediately before use. Several commercially available kits, such as the Vivaspin ultrafiltration system, can be used for this purpose.

The shelf life, under the storage conditions specified on the COA, begins from the date the product is received. Detailed information for each lot is provided on the lot-specific COA.

The concentration is determined by dividing the total weight of the lyophilized product by the volume of the bulk solution prior to lyophilization:

Concentration (mg/mL)=Weight of lyophilized product (mg)/Volume of solution (mL)

Fc-fused proteins inherently undergo Fc-driven dimerization in solution. For certain constructs, the structural characteristics of the fused domain may promote further oligomerization, yielding higher-order assemblies (e.g., trimers, multimers, or large polymers). The resulting molecular weight distribution is typically evident in non-reducing SDS-PAGE patterns or SEC chromatograms, where discrete species can be resolved.

The endotoxin level measured in the bulk solution is generally representative of the endotoxin level in the final lyophilized product. Based on our experience, endotoxin values obtained from lyophilized material may appear approximately 20–30% higher than those of the bulk solution. This variation is within the expected range and is primarily attributable to the increased sample amount required for testing and the influence of purity factors following lyophilization.

Our freeze-drying process is conducted under strictly controlled, sterile, and pyrogen-free conditions. Therefore, the endotoxin level of the bulk solution can be used as a reliable indicator of the endotoxin level of the corresponding lyophilized product.

Most ACROBiosystems proteins are formulated without carrier proteins; only a small number include BSA. Please refer to the buffer information on the product webpage for product-specific details.

ACROBiosystems’ biotinylated proteins use site-specific Avi-tag labeling, which places a small biotin molecule outside the functional domain. The labeling degree is optimized for each protein to maintain bioactivity while maximizing detection. Functional integrity is confirmed through binding assays such as ELISA, FACS, or cell-based tests, making it highly unlikely that labeling affects protein activity.

Biotinylated proteins from ACROBiosystems undergo purification to remove free biotin. Any residual biotin present is minimal and unlikely to interfere with downstream applications.

The trehalose used by ACROBiosystems is injection grade and is further diluted during experimental use. Under these conditions, it is not expected to affect cell behavior. For experimental rigor, we recommend including a buffer-only control group to account for any potential effects.

HEK293 cells (human embryonic kidney 293) provide protein folding and post-translational modifications that closely mimic native human proteins. Since the majority of ACROBiosystems’ proteins are human disease-related targets or factors, using the HEK293 expression system ensures biologically relevant conformation and functionality, supporting accurate downstream assays and applications.

Integrins are obligate heterodimers composed of alpha and beta chains, with transmembrane helices mediating their dimerization in native proteins. For the extracellular domain constructs we produce, Acidic and Basic tails are introduced to stabilize the heterodimer formation. These complementary charged tails promote proper heterodimer assembly, ensuring the correct integrin structure without adversely affecting protein activity.

His-tagged proteins are typically purified using Immobilized Metal Affinity Chromatography (IMAC), which selectively binds the histidine residues on the protein. For production, IMAC resins from reputable vendors such as GE and Qiagen are employed to achieve high purity while maintaining protein integrity and functionality.