Possible Interaction: Cysteine and Omeprazole

“ Omeprazole , the first acid pump inhibitor, forms a disulfide bond with cysteines in the extracytoplasmic loop between the fifth and sixth membrane-spanning segment and to a cysteine in the extracytoplasmic loop between the seventh and eight segments, preventing phosphorylation of the pump by ATP.”

“Our results demonstrate that omeprazole inhibits giardial triosephosphate isomerase in a species-specific manner through interaction with cysteine at position 222.”

“Some PPIs, such as omeprazole and rabeprazole bind to cysteines that are exposed, and their binding can be reversed.”

“Of interest, subsequent exposure of the stomach to a mercaptane compound cysteine , 100 mg/kg) for 30 min significantly reversed the antisecretory effect of omeprazole (both i.d.”

“Biological reducing agents like cysteine or glutathione, however, were unable to reverse the inhibitory effect of omeprazole.”

“However, the deduced amino acid sequences of the amplification refractory mutation system (ARMS) PCR product of the AcrR gene revealed that the substitution of arginine to cysteine at position 45 of AcrR was observed only in the MDR E. coli whose antibiotic susceptibility increased in the presence of omeprazole.”