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ARS Home » Southeast Area » Little Rock, Arkansas » Microbiome and Metabolism Research Unit » Research » Publications at this Location » Publication #164662
Title: PEANUT PROTEIN ALLERGENS: II. GASTRIC DIGESTION IS CARRIED OUT EXCLUSIVELY BY PEPSIN

Author
item KOPPER, RANDALL - HENDRIX UNIVERSITY
item ODUM, N - HENDRIX STUDENT
item SEN, MOON - UAMS
item HELM, RICKI - ACNC/UAMS
item STANLEY, STEVE - UAMS
item BURKS, WESLEY - UAMS/ACH

Submitted to: Journal of Allergy Clinical Immunology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/3/2004
Publication Date: 8/3/2004
Citation: Kopper, R.A., Odum, N.J., Sen, M., Helm, R.M., Stanley, S., Burks, W.A. 2004. Peanut protein allergens: II. gastric digestion is carried out exclusively by pepsin. Journal of Allergy Clinical Immunology. 114(3):614-618.

Interpretive Summary: A prominent characteristic of known food allergens is to that they have substantial protein stability to enzymatic digestion. Although readily soluble, peanut allergens form stable oligomers that are maintained by hydrophobic interactions that may contribute to their resistance to proteolysis. In vitro simulated pepsin digestion do not necessarily reflect the physiological digestion in vivo. Porcine gastric fluid is an extremely active protease and the gastric physiology of the swine is very similar to that of the human digestive tract. Assessment of the major peanut allergen, Ara h 1, either as an intact protein or as a peanut protein extract with porcine gastric fluid or pepsin demonstrated that the most single active protease in the stomach was pepsin. This in vivo model could be used to determine the relative digestive characteristics of novel proteins compared to known food allergens.

Technical Abstract: Background: A major characteristic of many food allergens, including Ara h1, a major peanut allergen, is their resistance to gastric digestion. One estimate of the allergenic potential of a possible protein allergen is its stability under simulated gastric conditions. Objective: Since the rate and extent of digestion of allergenic proteins will affect the severity of any subsequent allergic response, it is important to correlate protein allergen digestion in simulated gastric fluid with that in actual gastric fluid. Methods: A major peanut allergen, Ara h 1, was digested in vitro using both pepsin and porcine gastric fluid. Several comparisons between the two sets of proteolytic conditions were assessed including pH optima and the effect of temperature, denaturants, and specific enzyme inhibitors. Results: In vitro digestion of Ara h 1 with pepsin and porcine gastric fluid resulted in virtually identical hydrolysis patters as observed on SDS-PAGE. The protease activity of both pepsin and gastric fluid were inhibited at high pH and in the presence of pepstatin. However, both remained active in 4 M urea and at 60 degrees Celsius. Conclusions: Protein digestion in the porcine stomach is carried out by pepsin. In vivo gastric digestion is modeled accurately by peptic hydrolysis. Digestion conditions in vivo are comparable to experimental conditions in vitro provided that the acidic nature of stomach contents is optimal for characterization of the allergen under standard pepsin digestion conditions. Additional experimentation using crude food extracts, both in the presence and absence of a complete meal, is needed to elucidate the complete physiological nature of food allergen digestion. Key words: peanuts, food allergy, gastric digestion