Abstract

Celiac disease is an autoimmune disorder triggered by toxic peptides derived from incompletely digested glutens in the stomach. Peptidases that can digest the toxic peptides may formulate an oral enzyme therapy to improve the patients’ health condition. Bga1903 is a serine endopeptidase secreted by Burkholderia gladioli. The preproprotein of Bga1903 consists of an N-terminal signal peptide, a propeptide region, and an enzymatic domain that belongs to the S8 subfamily. Bga1903 could be secreted into the culture medium when it was expressed in E. coli. The purified Bga1903 is capable of hydrolyzing the gluten-derived toxic peptides, such as the 33- and 26-mer peptides, with the preference for the peptide bonds at the carbonyl site of glutamine (P1 position). The kinetic assay of Bga1903 toward the chromogenic substrate Z-HPQ-pNA at 37 °C, pH 7.0, suggests that the values of Km and kcat are 0.44 ± 0.1 mM and 17.8 ± 0.4 s−1, respectively. The addition of Bga1903 in the wort during the fermentation step of beer could help in making gluten-free beer. In summary, Bga1903 is usable to reduce the gluten content in processed foods and represents a good candidate for protein engineering/modification aimed to efficiently digest the gluten at the gastric condition.

Highlights

  • Gluten refers to the water-insoluble proteins in the flour of wheat, barley, and rye, and it may account for 70%–80% of the flour proteins [1]

  • According to clinical symptoms and pathological mechanisms, the discomforts and diseases caused by gluten consumption can be classified into celiac disease, wheat allergy, and non-celiac gluten sensitivity (NCGS) [2,3,4]

  • The clarified broth after centrifugation was tested for peptidase activity by gliadin zymography, which enabled us to detect the number of the secreted peptidases and their relatively activities and molecular sizes

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Summary

Introduction

Gluten refers to the water-insoluble proteins in the flour of wheat, barley, and rye, and it may account for 70%–80% of the flour proteins [1]. The ethanol soluble ones are called prolamins because they have high contents of proline and glutamine. The prolamins in wheat, barley, and rye are called gliadin, hordein, and secalin, respectively. Gluten in the flour is a valuable nutrient. It may cause health problems to certain people. According to clinical symptoms and pathological mechanisms, the discomforts and diseases caused by gluten consumption can be classified into celiac disease, wheat allergy, and non-celiac gluten sensitivity (NCGS) [2,3,4]

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