Pepsin resistance

Tanaka K, Matsumoto K, Akasawa A, et al. (2002). Pepsin-resistant 16-kD buckwheat protein is associated with immediate hypersensitivity reaction in patients with buckwheat allergy. Int. Arch. Allergy Immunol, 129 49-56. 

V.B12 is also known as antipemicious anemia factor. Pernicious anemia is characterized by a severely reduced production of red blood cells, deficient gastric secretion and disturbances of the nervous system. It is not usually caused by dietary deficiency of V.B]2, but by the absence of intrirrsic factor, which is required for V.B[2 absorption. Intrinsic factor is a neuraminic acid-containing glycoprotein, normally present in the gastric mucosa, which forms a pepsin-resistant complex with V.B,2, and enables V.B,2 absorption in the lower part of the intestinal traet. 

The aim of this study was to verify previous conclusions that dentin collagen resists enzymatic attack after reaction with glucose. The results show that, following the Maillard reaction, dentin collagen indeed is less degraded by pepsin, but not by trypsin. 

Chapter 4 describes the in vitro reaction of glucose wifh demineralized dentin. Preliminary tests revealed that use of disfilled insfead of deionized water accelerated browning, consistent with the effect of frace metals on the Maillard reaction. The yellow discolored slices were more resistant than controls to pepsin-mediated breakdown, but not to trypsin-mediated breakdown. It would be worthwhile to investigate proteolysis of denfin collagen covalently bound by the Maillard reaction to proteins, which penetrate into a caries lesion. 

One of the questions evolving from the results of Chapters 3 and 5 is If C(, sugars are not involved in the Maillard reaction, which compounds are In addition, is the glycosylated dentin as resistant to proteolysis by cariogenic bacteria as it is to pepsin in vitro ... 

Ribonuclease Ti is fairly resistant to proteases. The threonine residue at the carboxyl terminal of the enzyme can be removed by carboxy-peptidase A without loss of activity (67). Leucine aminopeptidase does not release amino acids from the amino terminal (68). Ribonuclease Ti is not inactivated by trypsin or chymotrypsin in the presence of 0.2 M phosphate (69), which probably binds the enzyme and protects it from inactivation (67). Treatment of the enzyme with trypsin in the absence of phosphate inactivates it (67). Ribonuclease Tj is hydrolyzed by pepsin with progressive loss of activity (69). 

In vitro rumen fermentation of the heated alfalfas showed (Table V) a decrease in organic matter digestibility (OMD) which was of the same order of magnitude as the increase in NDIN, suggesting that the NDIN fraction was resistant to microbial attack at rumen pH (6.9). The addition of HCl-pepsin to give a pH of... 

Deglycosylation had no marked effect on the stability of the acid carboxypeptidase. Both native and deglycosylated enzymes were stable up to 50°C and active in the presence of 4 M urea after 24 h. The molecular structures of both enzymes were not impaired by pepsin at pH 2.5 (Figure 25). These two enzymes had similarly great resistance to peptic digestion after 24h. 

Wang CY, Ye SQ, Dai L et al (2007) Enhanced resistance of polyelectrolyte multilayer microcapsules to pepsin erosion and release properties of encapsulated indomethacin. Biomacromolecules 8 1739-1744... 

Asero, R., Mistrello, G., Roncarolo, D. et al. 2000. Lipid transfer protein A pan-allergen in plant-derived foods that is highly resistant to pepsin digestion. Int Arch Allergy Immunol 122 20-32. 

Caballero, M.L. and Moneo, I. 2004. Several allergens from Anisakis simplex are highly resistant to heat and pepsin treatments. Parasitol Res 93(3) 248-251. 

In terms of oral systems for peptide delivery, modern formulation technology ensures that the activity of pepsin can be avoided by using polymeric enteric coatings to protect the target pharmaceutical peptide. These coatings are resistant to the acid environment of the stomach but dissolve when the pH rises in the small intestine. It is absolutely essential that any formulation being considered for the oral delivery of therapeutic peptides be coated with such materials to ensure that the peptide is protected from the action of pepsin. 

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