1. Pepsin solutions were iodinated at pH 5.0-6.0 until 10-20 per cent of the activity was lost and 1/20 (0.7 per cent) of the saturating amount of iodine had been introduced into the protein molecule. After alkaline hydrolysis 65 per cent of the original iodine was accounted for as mono-iodotyrosine although only 42 per cent was isolated as a crystalline product. No evidence was obtained to sup...

A system for the production of soluble porcine pepsinogen A (EC 3.4.23.1) was developed by fusing the pepsinogen and thioredoxin genes and then expressing the fused product (Trx-PG) in Escherichia coli. The expressed fusion protein was purified using a combination of ion-exchange and hydrophobic chromatography. Trypsin digestion of the fusion protein yielded pepsinogen which was one residue lon...

The secretion of pepsin in the gastric juice of patients with peptic ulcer has been the subject of much investigation. Early work was carried out mainly on resting juices or on the aspirated products of an Ewald meal (Willcox, 1908; Boas, 1925; Hirsch-Mamroth and Rindfleisch, 1925; Polland and Bloomfield, 1930; Vanzant, Osterberg, Alvarez, and Rivers, 1933; Mullins and Flood, 1935), and appeare...

The irreversible disappearance of the activity of pepsin in alkaline solution was first recorded by Kfihne (1). I t was confirmed by Langley (2), who observed also " tha t the destruction by sodium carbonate solutions goes on very much more slowly at 15°C. than at body temperature." Langley's experiments were carried out with neutralized filtrates of extracts of rabbit gastric mucosa made with ...

Several substrate-like epoxides were found to act as specific and irreversible inactivators of pepsin. Of these, 1,2-epoxy-3-(p-nitrophenoxy) propane (EPNP) was the most potent. When EPNP reacted with pepsin, all enzyme activity was lost. Two molecules of EPNP were found to be covalently bound to each molecule of completely inactivated enzyme. In this reaction, two carboxyl groups of the enzyme...

Several substrate-like epoxides were found to act as specific and irreversible inactivators of pepsin. Of these, 1,2-epoxy-3-(p-nitrophenoxy) propane (EPNP) was the most potent. When EPNP reacted with pepsin, all enzyme activity was lost. Two molecules of EPNP were found to be covalently bound to each molecule of completely inactivated enzyme. In this reaction, two carboxyl groups of the enzyme...

Laryngopharyngeal or gastroesophageal reflux is associated with laryngeal airway hyperreactivity (LAH), but neither the cause-effect relationship nor the underlying mechanism has been elucidated. Here we established a rat model with enhanced laryngeal reflex reactivity induced by laryngeal acid-pepsin insult and investigated the neural and hydroxyl radical (*OH) mechanisms involved. The larynge...

A revised method to determine solubility of nitrogen in dilute pepsin, using 0.0002% pepsin in place of 0.2% in AOAC Official Method 971.09, was tested in 16 laboratories with 12 samples of fishmeal. Results were calculated according to 2 procedures: AOAC Official Method 971.09 and a method described in 1964 by researchers at the Torry Research Station (Aberdeen, Scotland), and generally referr...