Release of opioid peptides, gluten exorphins by the action of pancreatic elastase.

The release of opioid peptides, gluten exorphins A, which have been isolated from the pepsin-thermolysin digest of wheat gluten, with gastrointestinal proteases was examined. High levels of gluten exorphin A5 (Gly-Tyr-Tyr-Pro-Thr) immunoreactive materials were detected in the pepsin-pancreatic elastase digest by a competitive ELISA. From this digest, gluten exorphin A5, B5 and B4 were isolated. This means that these peptides are released in the gastrointestinal tracts after ingestion of wheat gluten. The yield of gluten exorphin A5 in the pepsin-elastase digest was larger than that in the pepsin-thermolysin digest. The gluten exorphin A5 sequence is found 15 times in the primary structure of the high molecular weight glutenin. The region from which gluten exorphin A5 was released by the action of pancreatic elastase was identified using synthetic fragment peptides.