Chemical studies of some mammalian gastrins

Abstract

Soon after the first two gastrins had been isolated from hog antral mucosa (Gregory & Tracy 1964), there began close collaboration between the Physiological Laboratory and the Robert Robinson Laboratories at Liverpool. This has continued throughout our work, and all the natural gastrin samples used in it were supplied by Professor Gregory. We are deeply indebted to him for the opportunity to build on his arduous, pioneer work and enjoy exploring the fascinating chemistry of the gastrins. A brief review of our initial work with the porcine gastrins may be helpful. The dual nature of the hormone was puzzling, because the two compounds GI and GII had the same amino acid composition and degradative studies gradually confined the difference between them to a small region near the middle of the molecule. In fact, the peptide chain is identical in the two molecules and porcine gastrin II is the phenolic sulphate ester of porcine gastrin I at the tyrosine residue (position 12 in the chain). Tyrosine- O -sulphate had previously been reported to be a constituent of a peptide released by thrombin from fibrinogen (Bettelheim 1954) and to occur as the free amino acid in human urine (Tallan, Bella, Stein & Moore 1955), but this was the first time that it had been found as a component of a peptide hormone.