Degradation of Human Epidermal Keratin by Fish Pepsin

Arch Dermatol Res. 1988;280(2):119-23. doi: 10.1007/BF00417716.


Stomach extract of Atlantic herring Clupea harengus, Atlantic salmon Salmo salar, cod Gadus morhua, redfish Sebastes marinus, and plaice Pleuronectes platessa, degraded human epidermal keratin effectively in vitro. The keratin-degrading activity of all extracts showed a pH optimum around 3.3-3.4, and sheets of plantar callus were degraded with about the same efficacy as keratin. Pepstatin sensitivity, heat lability, and the acidic pH optimum demonstrated that the keratin-degrading activity was pepsin. The keratin-degrading activity of cod stomach extract had a temperature optimum of around 42 degrees C at optimal pH, and showed a similar pH dependency with collagen as with keratin as substrate. The keratin-degrading activity of pepsin I and pepsin II purified from cod showed a pH optimum of 3.7 and 3.1, respectively, similar to that obtained with hemoglobin as substrate. Pig pepsin showed a pH optimum of about 2 with keratin, hemoglobin, and collagen as substrates. The present investigation demonstrates that fish pepsin is effective in degrading human epidermal keratin in vitro, and in a contemporary study the same was shown with fish trypsin. This may suggest a possible mechanism for the development of irritative hand eczema caused by exposure to fish and acidified fish material.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Caseins / metabolism
  • Fishes / physiology*
  • Hemoglobins / metabolism
  • Humans
  • Hydrogen-Ion Concentration
  • In Vitro Techniques
  • Keratins / metabolism*
  • Pepsin A / metabolism*
  • Stomach / enzymology
  • Swine
  • Temperature
  • Tissue Extracts


  • Caseins
  • Hemoglobins
  • Tissue Extracts
  • Keratins
  • Pepsin A