Gibco™ Mouse Leptin Recombinant Protein

Catalog No.	Quantity
PMP0013	1 mg

Catalog No. PMP0013 Supplier Gibco™ Supplier No. PMP0013

Description

Recombinant Protein

Carrier-Free Reconstitution: We recommend that this vial be briefly centrifuged prior to opening to bring the contents to the bottom. Reconstitute leptin in sterile, distilled water to a concentration of 1.0-5.0 mg/mL. Further dilutions should be made in aqueous buffers supplemented with carrier protein, such as 0.1-1.0% BSA. Storage: This lyophilized preparation is stable at room temperature for up to 3 weeks, but should be kept at -20°C for long term storage, preferably desiccated. Upon reconstitution, the preparation is stable for up to one week at 2°C to 8°C. For maximal stability, apportion the reconstituted preparation into working aliquots and store at -20°C. Avoid repeated freeze/thaw cycles.

Leptin is a 167 amino acid long protein hormone with important effects in regulating body weight, metabolism and reproductive function. Leptin is approximately 16 kDa in mass and encoded by the obese (ob) gene. Leptin is expressed predominantly by adipocytes, which fits with the idea that body weight is sensed as the total mass of fat in the body. Smaller amounts of leptin are also secreted by cells in the epithelium of the stomach and in the placenta. Leptin receptors are highly expressed in areas of the hypothalamus known to be important in regulating body weight, as well as in T lymphocytes and vascular endothelial cells. Leptin's effects on body weight are mediated through effects on hypothalamic centers that control feeding behavior and hunger, body temperature and energy expenditure. Leptin is involved in regulating food intake, energy expenditure, and adiposity through hypothalamic leptin receptors. Leptin promotes hematopoiesis, angiogenesis, wound healing, inflammation, immune responses, influences pubertal development and fetal growth. Studies have investigated the role of leptin in obesity, anorexia nervosa, insulin resistance, and hypertension. Leptin also has thermogenic actions and regulates enzymes of fatty acid oxidation. Severe hereditary obesity in rodents and humans can be caused by defects in leptin production.

Specifications

• Accession Number: P41160
• For Use With (Application): Bioactivity
• Formulation: 0.1% TFA with no preservative
• Gene ID (Entrez): 16846
• Molecular Weight (g/mol): 16.2 kDa
• Name: Mouse Leptin
• Purification Method: Purified
• Quantity: 1 mg
• Storage Requirements: -20°C
• Regulatory Status: RUO
• Endotoxin Concentration: <0.1 ng/μg
• Gene Alias: CD295 antigen; H-Leptin; HuB219; Lep; LEPD; LEP-R; Leptin; leptin (murine obesity homolog); leptin (obesity homolog, mouse); leptin precursor; Method: conceptual translation supplied by author.; OB; obese; obese protein; obese, mouse, homolog of; obesity; obesity factor; obesity protein; OB-R; OBS; truncated leptin
• Common Name: Leptin
• Gene Symbol: Lep
• Biological Activity: Determined active in the ob/ob mouse obesity model. The ob/ob mice were treated via intraperitoneal injection once daily at a dose of 5 μg Leptin/gm of body weight for 7 days. Significant effects on body weight, food consumption, and plasma glucose levels were observed compared to saline-treated controls.
• Product Type: Protein
• Conjugate: Unconjugated
• Species: Mouse
• Recombinant: Recombinant
• Sequence: Mouse Leptin recombinant protein contains 147 amino acids
• Content And Storage: -20°C
• Activity: Determined active in the ob/ob mouse obesity model. The ob/ob mice were treated via intraperitoneal injection once daily at a dose of 5 μg Leptin/gm of body weight for 7 days. Significant effects on body weight, food consumption, and plasma glucose levels were observed compared to saline-treated controls.
• Endotoxin Level: <0.1 ng/μg
• Shipping Condition: Approved for shipment on Wet or Dry Ice
• Expression System: E. coli
• Protein Family: Cytokines & Receptors
• Protein Form: Recombinant, Ligand
• Form: Lyophilized
• Protein Subtype: Lectins & Leptins, Other Proteins
• Research Category: Endocrinology, Signal Transduction
• Product Line: Gibco
• Purity or Quality Grade: >98% 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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