Gibco™ Human IFN-alpha A (alpha 2a) Recombinant Protein

Catalog No.	Quantity
PHC4814	8.4 x 10^6 units

Catalog No. PHC4814 Supplier Gibco™ Supplier No. PHC4814

Description

Recombinant Protein

Dilution Recommendation: Further dilutions should be made in medium or buffered solution containing carrier protein such as PBS with 0.1% BSA.

IFN alpha (Interferon alpha) is a Type I interferon belonging to a family of structurally related, species-specific proteins exclusive to vertebrates. The interaction of IFN-alpha with its receptor component result in the activation of a number of signaling pathways which are mainly involved in innate immune response against viral infection. In humans, the gene for IFN alpha is located on on chromosome 9. The type I interferons consist of 14 different alpha isoforms (subtypes with slightly different specificities), and single beta, omega, epsilon and kappa isoforms. Homologous molecules are found in many species, including rats and mice (and most mammals), and have been identified in birds, reptiles and fish species. IFN alpha is produced primarily by plasmacytoid dendritic cells, is a potent component of the anti-viral innate immune response and modulates adaptive immunity. Diseases associated with the dysfunction of IFN alpha include Hepatitis C and Hepatitis.

Specifications

• Accession Number: P01563
• For Use With (Application): Bioactivity
• Formulation: PBS with 0.1% BSA and no preservative
• Gene ID (Entrez): 3440
• Molecular Weight (g/mol): 19.2 kDa
• Name: Human IFN-alpha A (alpha 2a)
• Purification Method: Purified
• Quantity: 8.4 x 10^6 units
• Storage Requirements: -80°C
• Regulatory Status: RUO
• Gene Alias: alpha-2a interferon; Ifa2; IFNA; IFN-a; IFNA 2; Ifna2; IFNA2A; IFNA2B; IFNA2C; IFN-alpha 1b; IFN-alpha-1/13; IFN-alpha-2; IFN-alphaA; INFA2; Interferon; interferon alpha 1b; interferon alpha 2; interferon alpha 2a; interferon alpha 2b; interferon alpha A; interferon alpha family, gene 2; interferon alpha-2; Interferon alpha-A; interferon alpha-D; interferon, alpha 2; Interferon-alpha II; leIF A; leIF D; RP11-354P17.2
• Common Name: Interferon alpha-2
• Gene Symbol: IFNA2
• Biological Activity: Specific activity = 4.0 x 10e8 units/mg; Assay used to measure bioactivity: interferon was titrated with the use of the cytopathic effect inhibition assay as described [Rubinstein, S., Familletti, P.C., and Pestka, S. (1981'Convenient Assay for Interferons,' J. Virol. 37, 755-758; Familletti, P.C., Rubinstein, S., and Pestka, S. (1981)'A Convenient and Rapid Cytopathic Effect Inhibition Assay for Interferon,' in Methods in Enzymology, Vol. 78 (S. Pestka, ed.), Academic Press, New York, 387-394 ]. In this antiviral assay for interferon about 1 unit/mL of interferon is the quantity necessary to produce 50% cytopathic effect. The units are determined with respect to the international reference standard for human interferon-alphaA (Hu-IFN-α? provided by the National Institutes of Health [see Pestka, S. (1986)'Interferon Standards and General Abbreviations,' in Methods in Enzymology Vol. 119 (S. Pestka, ed.), Academic Press, New York, 14-23 ]. The activity was determined with bovine MDBK cells challenged with vesicular stomatitis virus (VSV).
• Product Type: Protein
• Conjugate: Unconjugated
• Species: Human
• Recombinant: Recombinant
• Content And Storage: -80°C
• Activity: Specific activity = 4.0x10e8 units/mg; Assay used to measure bioactivity: interferon was titrated with the use of the cytopathic effect inhibition assay as described [Rubinstein, S., Familletti, P.C., and Pestka, S. (1981 Convenient Assay for Interferons, J. Virol. 37, 755-758; Familletti, P.C., Rubinstein, S., and Pestka, S. (1981) A Convenient and Rapid Cytopathic Effect Inhibition Assay for Interferon, in Methods in Enzymology, Vol. 78 (S. Pestka, ed.), Academic Press, New York, 387-394]. In this antiviral assay for interferon about 1 unit/mL of interferon is the quantity necessary to produce 50% cytopathic effect. The units are determined with respect to the international reference standard for human interferon-alphaA (Hu-IFN-α? provided by the National Institutes of Health [see Pestka, S. (1986) Interferon Standards and General Abbreviations, in Methods in Enzymology Vol. 119 (S. Pestka, ed.), Academic Press, New York, 14-23]. The activity was determined with bovine MDBK cells challenged with vesicular stomatitis virus (VSV).
• Shipping Condition: Dry Ice
• Expression System: E. coli
• Protein Family: Cytokines & Receptors
• Protein Form: Recombinant, Ligand
• Form: Liquid
• Protein Subtype: Interferons
• Research Category: Immunology, Virology, Oncology, Signal Transduction
• Product Line: Gibco
• Purity or Quality Grade: >95% by SDS-PAGE

Frequently Asked Questions (FAQs)

What is the relationship between specific activity units and International Units of activity?

There is no direct correlation or calculation between specific activity unit and International Unit (IU) values. International Units (IU) express a quantification of activity for the base amount of a substance in relation to an analogous reference standard with an internationally accepted unit of biological potency (i.e., IU/ng) that has been assigned based on an International Collaborative Study conducted by the World Health Organization (WHO). WHO Reference Standards are made available by the National Institute for Biological Standards and Control (NIBSC). Intended to simplify the comparison of activity of a substance obtained from different sources, IU measurements can vary as comparison methods are rarely the same between sources. A true direct comparison requires standardized methods of analysis in order to guarantee comparability of the substance’s activity in relation to its mass across sources.

Why can't I see the protein pellet in the vial for my lyophilized recombinant protein? Is this normal?

Gibco recombinant proteins are frequently formulated without carrier proteins or additives (e.g., BSA, HSA, sucrose, etc.) and Gibco PeproTech recombinant proteins don't contain a carrier protein. As a result, during lyophilization, the protein product may be deposited on the vial as a thin, and sometimes invisible film instead of a pellet. The size of the pellet, if any, is not directly related to the quantity of the recombinant protein in the vial. Our quality control procedures assure that each vial contains the correct amount of product.

To ensure complete recovery of protein product, before opening a vial of lyophilized recombinant protein, we recommend centrifuging it in a microcentrifuge for 20-30 seconds to drive any protein that may be lodged in the cap or on the side or the bottom of the vial. After reconstitution, you can confirm the presence of product protein by running a small amount on SDS-PAGE. In general, a protein band with expected size should be visible with as little as 10 ng of protein loaded on an acrylamide gel.

Does a particular recombinant protein contain the wild-type or mutated amino acid sequence?

Protein sequence information is available on the individual product page, except for proprietary engineered proteins.

What kind of tubes should I use for storing aliquots of reconstituted recombinant proteins?

In general, we recommend using polypropylene tubes for storing aliquots of reconstituted recombinant proteins. Specific information for appropriate storage and handling of many recombinant proteins can be found on the product pages.

Does each lot of recombinant protein have the same specific activity?

No, each lot can vary slightly with regards to its specific activity. The information on the data sheet for each product is provided as a guide. For lot-specific information, please please check the Certificate of Analysis or contact Technical Support.

What is the specific activity of my recombinant protein?

The ED50 for each functionally active recombinant protein can be found on its product page under Activity as well as in the data sheet. The specific activity (units/mg) for each recombinant protein can be determined from the ED50 using information available in our Tech Tip here: https://assets.thermofisher.com/TFS-Assets/BID/Technical-Notes/converting-ed50-ng-ml-specific-activity-units-mg-tech-note.pdf

What is the shelf life of your recombinant proteins?

The majority of our recombinant proteins have a guaranteed shelf life of one year unless otherwise indicated in our technical data sheets. This guarantee applies only if the recombinant protein is stored under the conditions stated in the data sheet. If you are not completely satisfied with the performance of the product, please contact Technical Support at techsupport@thermofisher.com for assistance.

It looks like the recombinant protein vial I received from you is empty. Is this normal?

Gibco recombinant proteins are frequently formulated without carrier proteins or additives (e.g., BSA, HSA, sucrose, etc.) and no Gibco PeproTech recombinant protein contains a carrier protein. As a result, during lyophilization, the protein product may be deposited on the vial as a thin, and sometimes invisible, film instead of a pellet. The size of the pellet, if any, is not directly related to the quantity of the recombinant protein in the vial. Our quality control procedures assure that each vial contains the correct amount of product.

To ensure complete recovery of protein product, before opening a vial of lyophilized recombinant protein, we recommend centrifuging it in a microcentrifuge for 20-30 seconds to drive any protein that may be lodged in the cap or on the side to the bottom of the vial. After reconstitution, you can confirm the presence of product protein by running a small amount on SDS-PAGE. In general, a protein band with expected size should be visible with as little as 10 ng of protein loaded on an acrylamide gel.

Why does my recombinant protein not show activity in my own experiment?

Assay time is critical. Each assay needs to beoptimized and performed at the peak response time. Different cells may respond differently to a growth factor or cytokine. We suggest repeating our QC assay using same indicator cells as suggested in the manual to see if you can obtain a similar response. In addition, serum may be masking the response. Serum starvation might be needed for certain types of assays.

Why is my recombinant protein not soluble?

The solubility issue might be due to improper handling, or use of a solvent other than the one we recommended. We recommend that you warm the lyophilized powder to room temperature before you open the vial, and that you solubilize the protein in the buffer solution recommended in the manual (some proteins are more soluble in low pH buffer). Do not reconstitute at a protein concentration greater than 1 mg/mL. Do not vortex or mix protein solutions vigorously. Allowing the reconstituted protein to incubate overnight at 4 degrees C may help resolve any solubility issues.

Are Thermo Fisher Scientific recombinant proteins calibrated with the WHO Reference Standard?

Where possible, Thermo Fisher Scientific obtains International Unit (IU) values through multiple side-by-side comparisons of our product(s) against the analogous WHO Reference Standard within our biological activity assay. Performing multiple comparison tests allows us to account for any outliers due to possible variations with the assay (e.g., product handling, assay protocol, etc.). Using the results of these comparisons, we can provide a reliable quantification of our product’s activity in relation to the activity of the WHO Reference Standard.

Information pertaining to whether a specific product has been tested against the WHO Reference Standard can typically be located on the product page or COA.

What are the major differences between the recombinant proteins produced in different expression systems?

The recombinant proteins provided by Thermo Fisher Scientific are usually produced in different expression systems such as E. coli, insect cells, or mammalian cells. The major differences in recombinant proteins produced in different expression systems are in the post-translational modifications present, such as glycosylation. Recombinant proteins produced in E. coli are not glycosylated. Recombinant proteins produced in insect cells are partially glycosylated without galactose and sialic acid and not branched. Recombinant proteins produced in mammalian cells are fully glycosylated.

Note: Mimic Sf9 Insect Cells (a derivative of the Sf9 insect cell line that has been modified to stably express a variety of mammalian glycosyltransferases) can be used for production of complex N-glycans with terminal sialic acid and galactose.

Why do I have to freeze recombinant protein solutions in working aliquots?

Repeated freeze/thaws will affect the stability of the recombinant protein. For example, freezing will significantly affect the pH of the protein solution and might cause denaturation of the protein (Arch Biochem Biophys 384:398 (2000)).

How should I store the reconstituted recombinant proteins?

Protein solutions are generally not very stable when frozen at low concentration. Upon freeze and thaw, some proteins in the solution may stick to the wall of the container, which results in significant reduction of protein concentration if the starting concentration was low. Therefore, carrier proteins are used to reduce such loss. The most commonly used carrier proteins include bovine serum albumin (BSA), human serum albumin (HSA), or fetal bovine serum (FBS). These carrier proteins are generally used at 0.1% concentration. As a rule of thumb, if the concentration of the recombinant protein is less than 0.5 mg/mL, it is a good idea to add some carrier protein

How do I store my lyophilized recombinant protein?

Lyophilized proteins can typically be stored at 2 to 8 degrees C for several weeks, or stored dessicated at -20 degrees C for long-term storage.

Safety and Handling

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