Bismuth, Interaction with Gastrin
The peptide hormone gastrin was originally identified as a stimulant of acid secretion, but is now known to also act as a growth factor in the gastrointestinal tract (Dockray et al. 2001). Gastrin is synthesized as a precursor of 101 amino acids (preprogastrin) which, on removal of the signal peptide of 21 amino acids, yields progastrin (80 amino acids). Proteolytic processing in antral G cells in the stomach generates a number of intermediate peptides, including glycine-extended gastrin17 (Ggly), which has the sequence ZGPWLEEEEEAYGWMDFG. Transamidation of the C-terminal glycine yields the C-terminal amidated phenylalanine characteristic of amidated gastrin (Gamide). Both Ggly and Gamide are independently active, via different receptors, in the gastrointestinal tract.
Iron: Interaction with Gastrin
Fluorescence experiments have revealed that both Ggly and Gamide bind two ferric ions with high affinity (Kd= 0.6 μM, pH 4.0) in aqueous solution (Baldwin...