History of Prolyl Endopeptidases | AN-PEP

By Dante Moroni

Note: This article is non-peer reviewed and self published. Any statement within are for entertainment purposes and curiosity sake. In no way should any piece from this article be taken as medical advice. This article is also a work in progress and will be updated as necessary by the author.

In celiac disease (CD), the the immune system is activated by certain gluten derived immunogenic peptides. These peptides are the result of the breakdown of gluten subcomponents glutenin and gliadin into smaller peptide chains. What makes these gluten peptides special is their abundance of digestion resistant glutamine (Q) and proline (P) amino acid residues.1 Since our bodies do not have the ability to fully cleave and degrade these peptides during digestion, exogenous proline cleaving enzymes have been suggested as a remedy. Researchers are still looking into their potential role as a therapeutic in CD, in addition to using them for processing gluten containing foodstuffs into celiac safe versions.2 The first of these prolyl endopeptidases was discovered over 50 years ago and several others have been discovered since then, the most well known of which is Aspergillus niger prolyl endopeptidase (AN-PEP). To note, humans do make endogenous proline endopeptidases (PEP), which are highly concentrated in the brain, however they are not secreted into the digestive tract.6

Major Prolyl Peptidase Discoveries

1971: Walter Roderich and colleagues discover the first prolyl oligopeptidase extracted from human uterine tissue and it is shown to inactivate oxytocin by cleaving the bond between Proline and Leucine.4

1976: Walter then discovers and extracts a prolyl endopeptidase from lamb kidney. It works on certain Proline-X bonds.5

1976 : Oliveira et al Isolate Brain Kininase B from rabbit brain and find that it cleaves the bond between Proline and Phenylalanine in Bradykinin.3

1978 (FM-PEP): Yoshimoto and Tsuru build off of the work of Walter to find prolyl endopeptidase activity in a pathogenic bacteria, Flavobacterium meningosepticum.7 Has Pro-X activity similar to the lamb kidney PEP.

1998 (SC-PEP): Yoshimoto and colleagues continue to investigate prolyl endopeptidases and focus on one purified from Sphingomonas capsulata bacterium.9

2005 (AN-PEP): Kubota et al find the golden nugget, a robust prolyl endopeptidase from the fungus, Aspergillus niger, now widely known as AN-PEP8. This specific endopeptidase is what is used in brewing gluten reduced beer and is currently being tested for its use in celiac disease and other applications. It is available under several brand names, Brewers Clarex for use in brewing, and Gliadin X as a dietary supplement.

2010 (ALV003/Latiglutenase): A combination of SC-PEP and an Endoprotease from barley malt that is currently in phase 2 clinical trials for therapeutic potential in Celiac Disease.


  1. Hausch F, Shan L, Santiago N, Gray G, Khosla C. Intestinal Digestive Resistance of Immunodominant Gliadin Peptides. American Journal of Physiology. 2002;283: G996–G1003, 2002.
  2. Kumar B, Vijaykrishnaraj, Kurrey N, Shinde V, Prabhasankar P. Prolyl Endopeptidase-Degraded Low Immunoreactive Wheat Flour Attenuates Immune Responses in Caco-2 Intestinal Cells and Gluten-Sensitized BALB/c Mice. Food and Chemical Toxicology. 2019;129:466-475.
  3. Oliveira E, Marins A, Camargo A. Isolation of Brain Endopeptidases: Influence of Size and Sequence of Substrates Structurally Related to Bradykinin. Biochemistry. 1976;15:67-74.
  4. Walter R, Shlank H, Glass J, Schwartz I, Kerenyi T. Leucylglycinamide Released from Oxytocin by Human Uterine Enzyme. Science. 1971;173:827-829.
  5. Walter Roderich. Partial Purification and Characterization of Post-Proline Cleaving Enzyme. Biochim Biophys Acta. 1976;422:138-158.
  6. Kato T, Okada M, Nagatsu T. Distribution of Post-Proline Cleaving Enzyme in Human Brain and the Peripheral Tissues. Molecular Cell Biochemistry. 1980;32:117-121.
  7. Yoshimoto T, Tsuru D. Proline Specific Endopeptidase from Flavobacterium. Agricultural and Biological Chemistry. 1978;42:2417-419.
  8. Kubota K, Tanokura M, Takahashi K. Purification and Characterization of a Novel Prolyl Endopeptidase from Aspergillus niger. Proceedings of the Japan Academy. 2005;81.
  9. Kabashima T, Fujii M, Meng Y, Kiyoshi I, Toshimoto T. Prolyl Endopeptidase from Sphingomonas capsulata: Isolation and Characterization of the Enzyme and Nucleotide Sequence of the Gene. Archives of Biochemistry and Biophysics. 1998;358:141-148.


  1. Flavobacterium meningosepticum
  2. Aspergillus niger Fungus
  3. Aspergillus niger Colony