Page "Protein primary structure" Paragraph 59

Despite these data and later evidence that proteolytically digested proteins yielded only oligopeptides, the idea that proteins were linear, unbranched polymers of amino acids was not accepted immediately.

Some well-respected scientists such as William Astbury doubted that covalent bonds were strong enough to hold such long molecules together ; they feared that thermal agitations would shake such long molecules asunder.

Hermann Staudinger faced similar prejudices in the 1920s when he argued that rubber was composed of macromolecules.