Invitrogen™ Normal Goat Serum

Catalog No.	Quantity
PI31873	600 mg
PI31872	120 mg

Catalog No. PI31873 Supplier Invitrogen™ Supplier No. 31873

Description

Goat Control

For blocking purposes, use 5% (v/v) solution (1:20 dilution from rehydrated volume). Rehydration according to instruction yields 100% serum. Restoration and Storage: Store product at 4°C until opened. Restore with distilled water: 10.0 mL (600 mg package size) and 2.0 mL (120 mg package size). Centrifuge product if it is not completely clear after standing for 1-2 hours at room temperature. Product may be stored for up to several weeks at 4°C as an undiluted liquid. After dilution, do not use for more than one day. To extend the shelf-life of this product, freeze rehydrated undiluted product in small aliquots at -20°C. Country of Origin: USA.

Normal Sera are non-immune serum samples from goat, human, mouse, rabbit and other species that contain the usual complement of serum proteins, including the various classes of immunoglobulins that exist in healthy animals of the particular species. Normal serum provides a sufficient quantity of endogenous proteins to saturate and block nonspecific binding sites on fixed samples or assay substrates. When used as an antibody diluent, non-immune serum also supplies a native chemical environment for antibodies to function properly without adding foreign protein components. Normal serum is frequently used for blocking or saturating generalized binding interactions for immunodetection methods, especially those involving tissue samples such as immunohistochemistry (IHC). Normal sera are also useful as controls for testing general and specific antibody purification methods.

Specifications

• Content And Storage: 4°C
• Form: Lyophilized
• Product Type: Normal Goat Serum
• Quantity: 600 mg
• Concentration: 60.0 mg/mL
• Sterility: Sterile
• Formulation: Whole serum, PBS with 0.05% sodium azide; pH 7.6
• For Use With (Application): Control, Immunocytochemistry, Immunohistochemistry, Blocking Assay
• Isotype: Ig
• Regulatory Status: RUO

Frequently Asked Questions (FAQs)

The antibody I purchased from you says ''concentration not determined'' on the product label and on the product page. How do I determine the concentration?

Some antibodies are provided in non-purified formats, such as ascites fluid, tissue culture supernatant, or whole serum. These formats contain multiple proteins, which can interfere with accurate protein quantification. Traditional methods like A280 measurement or protein assays such as BCA quantify total protein but do not provide a specific concentration for the antibody in question.

Literature, such as "Antibodies" by Harlow & Lane (1988) (https://antibodiesmanual.org/index.php) (Table 8.2 - Storing and Purifying Antibodies), suggests approximate concentrations of antibodies in these solutions, as shown below. However, please note that these are rough estimates, and actual concentrations can vary based on several factors.

Serum
Total antibody concentration: 10 mg/mL
Specific antibody concentration: 0.1 to 1 mg/mL (a maximum of 10% of the antibody population is expected to be the specific antibody of interest)

Tissue Culture Supernatant (10% FBS)
Total antibody concentration: 1 mg/mL
Specific antibody concentration: 0.05 mg/mL

Tissue Culture Supernatant (serum-free)
Total antibody concentration: 0.01 to 0.05 mg/mL
Specific antibody concentration: 0.01 to 0.05 mg/mL

Ascites
Total antibody concentration: 1 to 10 mg/mL
Specific antibody concentration: 0.9 to 9 mg/mL

When would I use goat, horse, or chicken serum for blocking versus FBS or BSA?

For blocking, you should use a serum of the same or closely related species of the secondary antibody being used. If using a secondary antibody that was raised in goat or sheep, use goat serum (Cat. No. R37624 or 31873) for blocking; if using a secondary antibody raised in donkey or horse, use horse serum (Cat. No. R37625 or 31874) for blocking; if using a secondary antibody raised in chicken, use chicken serum (Cat. No. R37626) for blocking. FBS and BSA are alternatives when a specific species of serum is not available.

I used a neuron-specific antibody to label my neurons. How can I reduce non-specific antibody binding?

A blocking step should be performed to reduce fluorescence due to non-specific antibody binding. A common blocking step is the addition of a 2-5% solution of bovine serum albumin (fraction V defatted BSA). Another approach employs the addition of a 5-10% solution of serum from the species in which the secondary antibodies were raised. For example, when using goat anti-mouse IgG secondary antibodies, samples may be effectively blocked with 5-10% normal goat serum. To further reduce background fluorescence, the Image-iT FX Signal Enhancer can be included as a pre-blocking step to decrease non-specific labeling due to charge interactions between the dyes on the conjugates and the cellular constituents.
If you are using a secondary antibody make sure that the species of the antibody is not the same as the species of the sample. For example do not use an anti-mouse secondary antibody on mouse tissue.
Titrate the antibody to the lowest concentration you can use and still get adequate signal.
Try using a fluorescently tagged primary antibody because it should give reduced background but be aware this can reduce signal intensity.

After labeling with my antibody, I am seeing non-specific background binding in my cells or tissue. What could be the cause?

There can be many causes, including insufficient blocking, too high a concentration of the primary or secondary antibody, or degraded primary or secondary antibody. A “no-primary antibody” control can help determine if the secondary antibody is at fault. Otherwise, we recommend trying more stringent blocking or lower concentrations of primary and secondary antibodies.

What concentration of my antibody should I use for cell analysis?

An optimal concentration may be between 1-10 µg/mL for cell and tissue labeling for microscopy, or 0.2-5 µg/mL for flow cytometry. A range of concentrations should be tested to determine what is optimal.

I know I need to block my samples against non-specific protein binding of my antibodies, but which blocker should I use?

For blocking cells or tissues you may use 2-5% bovine serum albumin (fraction V, defatted BSA) or 5-10% normal serum of the species matching the host species of the secondary antibody. Other options include a mixture of BSA and serum or other purified proteins. We offer a ready-made blocking solution, BlockAid Blocking Solution (Cat. No. B10710), which is not species-specific. For cell or tissue samples, avoid the use of non-fat dry milk as a blocking agent as it contains a high level of phosphoproteins, histones, and biotin.