Isolation and evolution of the gastrointestinal hormones.

The history of the discovery of gastrointestinal hormones and the modern methods of their isolation are discussed in the first chapter. The origin of structural relationships of gastrointestinal hormones and the possible ways of evolution are analyzed in the second chapter. The methods used for isolation and identification of secretin and cholecystokinin are dealt with in detail; the isolation of vasoactive intestinal peptide, gastrin, "gastric inhibitory peptide" and enteroglucagon is discussed but briefly in the first chapter. The second chapter is of speculative character. It deals with the structural resemblances between gastrin-type (gastrin, cholecystokinin-pancreozyzimin, caerulein) and secretin-type (secretin, vasoactive intestinal peptide, glucagon, "gastric inhibitory peptide") hormones. The resemblances are explained by different evolutionary mechanisms.