MILPITAS, Calif. -
July 11, 2018 -
PRLog -- Pepsin (EC 3.4.23.1) is a peptidase A1 family aspartic protease that serves as a primary digestive enzyme in the mammalian stomach. Pepsin is synthesized in the chief cells of the gastric mucosa as the inactive pro-enzyme pepsinogen, which contains a 44 amino acid autoinhibitory domain. The proenzyme is packaged into granules and stored inside the gastric mucosal cells. When food is consumed, neuronal signals traveling along the vagus nerve trigger secretion of HCl and pepsinogen into the stomach. In the highly acidic environment of the stomach, pepsinogen unfolds and undergoes autocatalytic cleavage, forming the active protease pepsin. Infection by the bacterium H. pylori induces hypersecretion of both stomach acid and pepsin, contributing to the formation of gastric and duodenal ulcers. In addition, excessive amounts of pepsin can play a role in the degradation of the esophageal and laryngeal tissue observed in chronic gastroesophageal reflux disease. While the majority of pepsinogen is expressed in the gastric mucosa, a small amount of the inactive enzyme is also released into the blood. Serum pepsinogen levels correlate with functional changes to gastric mucosa and are often measured for the screening of gastric cancer and chronic H. pylori-induced gastritis. BioVision's Pepsin Assay Kit is a homogenous assay that allows for quantification of pepsin activity in gastric tissue and various biological fluids. The assay utilizes a synthetic peptide substrate bearing both a fluorophore and a fluorescence quencher. Upon cleavage by pepsin, the fluorophore-
bearing peptide fragment is unquenched to produce a bright fluorescent signal (Ex/Em = 328/418 nm). Lysosomal aspartic proteases in the peptidase A1 family (Cathepsin D and E) do not interfere with the assay. The assay is rapid, simple to perform and is vastly more sensitive than the classical hemoglobin degradation assay, with a detection limit of 500 μU pepsin activity per well.
FIGURE: Estimation of pepsinogen activity (K446-100) in pooled normal human serum and single-donor serum from a gastric ulcer patient with confirmed H. Pylori infection (each 10 μl of undiluted serum). Data are mean ± SEM of 3 replicates, assayed according to the kit protocol.
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https://www.biovision.com/trypsin-activity-colorimetric-a... for complete information on this kit.
