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Technical Info


Enzyme Research Laboratories make the following suggestions for the storage and handling of purified proteins:

  1. Most purified proteins in solution are stable at low temperatures and should be stored at < -60°C.
  2. Lyophilized proteins should be reconstituted using a good laboratory quality H2O. After reconstitution the protein should be aliquoted into a useful (one time use) size and stored at < -60°C.
  3. Proteins should be frozen in a concentrated form when possible. When dilution is necessary dilute immediately prior to use. When possible, dilution buffers should contain stabilizers such as albumin.
  4. Thawing and refreezing should be kept to a minimum. Multiple freeze / thaw cycles can reduce protein activity and cause degradation. We always suggest aliquoting the protein into a single use size.
  5. Refrigerate thawed proteins or store on ice. Proteins warmed even to room temperature may degrade quickly.
  6. One exception to # 5 is Fibrinogen. After thawing Fibrinogen should be kept at room temperature. Fibrinogen will come out of solution if it is cooled.
  7. Products provided in Glycerol / buffer solutions should be stored at -20°C. Temperatures below -30°C can cause phase transitions and should to be avoided.



  • 1 PEU (Plasma Equivalent Unit) is equal to the amount of activity found in one mL of plasma as determined in a factor deficient clotting assay.
  • All extinction coefficients are reported for 280 nm using 1 cm path length.


ANTIBODY USE (general recommendations)

The optimal concentration of antibody for any particular application will vary depending on the antibody format as well as the detection method used. We strongly suggest each antibody be titrated by the end user to determine the optimal working concentration for each particular application. The following chart contains general recommendations only and may not apply to all products.


Format Immunoblotting
(ECL detection)
Whole IgG (IG) 5-25 ug/mL 20-50 ug/mL NA
Affinity-Purified (AP-IgG) 0.5-5 ug/mL 10 ug/mL NA
IgG Peroxidase (HRP) 5 ug/mL NA 10 ug/mL
AP-IgG Peroxidase (AP-HRP) 1 ug/mL NA 2 ug/mL



All Human Source material is tested and found negative for all communicable diseases, including HIV-1 and HIV-2 antibodies, HCV, Rapid Plasma Reagin and Hepatitis B Surface Antigen. Because no test method can offer complete assurance that Human Immunodeficiency Virus (HIV), Hepatitis B virus or other infectious agents are absent, all human proteins should be handled as suggested in the U.S. Department of Health and Human Services Manual on Biosafety in Microbiological & Biomedical Laboratories.

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