ab181677 is an IgG fraction antibody purified from monospecific antiserum by a multi-step process which includes delipidation, salt fractionation and ion exchange chromatography followed by extensive dialysis against the buffer stated.
Pepsin is a digestive enzyme with particularly broad specificity. It is stored as pepsinogen, so only released when needed. In the stomach, chief cells release pepsinogen. The hormone gastrin and the vagus nerve trigger the release of both pepsinogen and HCl from the stomach lining when food is ingested. HCl creates an acidic environment which allows pepsinogen to unfold and cleave itself in an autocatalytic fashion, thereby generating pepsin (the active form). Pepsin may then cleave the dietary proteins into smaller peptides.