MOLECULAR CONFORMATION INFLUENCE ON TRANSPORT PROCESSES AND RECEPTOR BINDING OF GASTRIN; A NEW SCHEME OF GASTRIC SECRETORY REGULATION

Publisher Summary This chapter discusses the molecular conformation influence on transport processes and receptor binding of gastrin. In an experiment described in the chapter, synthetic pentagastrin was covalently coupled to human blood serum albumin with addition of toluilendiisocyanate. The conjugate and free hormone was separated by gel filtration on Sephadex G-50. Amino acid analysis established that one albumin molecule was bound to 19 gastrin peptide molecules. One mg of the conjugate contained 14 mcg of gastrin peptides. This bound pentagastrin seemed to be the same as gastrin bonding to membrane of parietal cells. It is believed that gastrin is subject to the attack of enzyme only after a change of its conformation by immunoglobulin G. One gastrin complex, that is, gastrin–parietal cell membrane complex, has to be replaced by another gastrin-immunoglobulin complex. This seems to be the situation in nature. If this is true, then synthetic gastrin–human albumin complex cannot stimulate gastric secretion, because gastrin behaves as if it were bound to cell membrane and remains to be removed.