 A key testable prediction was that a folded protein's carbonyl groups should be largely converted to hydroxyl groups; however, spectroscopic and chemical experiments showed that this prediction was incorrect.The cyclol model also predicts a high lateral density of amino acids in folded proteins and in films that does not agree with experiment.Hence, the cyclol model could be rejected and the search begun for new hypotheses of protein structure, such as the models of the alpha helix proposed in the 1940s and 1950s.