Safety assessment of the calcium-binding protein, apoaequorin, expressed by Escherichia coli

Regul Toxicol Pharmacol. 2014 Jul;69(2):243-9. doi: 10.1016/j.yrtph.2014.04.004. Epub 2014 Apr 24.


Calcium-binding proteins are ubiquitous modulators of cellular activity and function. Cells possess numerous calcium-binding proteins that regulate calcium concentration in the cytosol by buffering excess free calcium ion. Disturbances in intracellular calcium homeostasis are at the heart of many age-related conditions making these proteins targets for therapeutic intervention. A calcium-binding protein, apoaequorin, has shown potential utility in a broad spectrum of applications for human health and well-being. Large-scale recombinant production of the protein has been successful; enabling further research and development and commercialization efforts. Previous work reported a 90-day subchronic toxicity test that demonstrated this protein has no toxicity by oral exposure in Sprague-Dawley rodents. The current study assesses the allergenic potential of the purified protein using bioinformatic analysis and simulated gastric digestion. The results from the bioinformatics searches with the apoaequorin sequence show the protein is not a known allergen and not likely to cross-react with known allergens. Apoaequorin is easily digested by pepsin, a characteristic commonly exhibited by many non-allergenic dietary proteins. From these data, there is no added concern of safety due to unusual stability of the protein by ingestion.

Keywords: Allergenicity; Apoaequorin; Bioinformatic; Calcium-binding protein; Safety assessment.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aequorin / administration & dosage
  • Aequorin / biosynthesis
  • Aequorin / genetics*
  • Aequorin / immunology
  • Aequorin / toxicity*
  • Allergens / immunology
  • Amino Acid Sequence
  • Animals
  • Apoproteins / administration & dosage
  • Apoproteins / biosynthesis
  • Apoproteins / genetics*
  • Apoproteins / immunology
  • Apoproteins / toxicity*
  • Calcium-Binding Proteins / administration & dosage
  • Calcium-Binding Proteins / biosynthesis*
  • Calcium-Binding Proteins / immunology
  • Calcium-Binding Proteins / toxicity*
  • Computational Biology
  • Escherichia coli / genetics*
  • Escherichia coli / metabolism
  • Gastric Mucosa / metabolism
  • Molecular Sequence Data
  • Pepsin A / metabolism
  • Protein Stability
  • Rats
  • Recombinant Proteins / administration & dosage
  • Recombinant Proteins / biosynthesis
  • Recombinant Proteins / genetics
  • Recombinant Proteins / immunology
  • Recombinant Proteins / toxicity
  • Risk Assessment
  • Safety*
  • Toxicity Tests, Subchronic


  • Allergens
  • Apoproteins
  • Calcium-Binding Proteins
  • Recombinant Proteins
  • apoaequorin
  • Aequorin
  • Pepsin A