Having proposed a model of globular proteins, Wrinch investigated whether it was consistent with the available structural data. She hypothesized that bovine tuberculin protein (523) was a C closed cyclol consisting of 72 residues and that the digestive enzyme pepsin was a C closed cyclol of 288 residues. These residue-number predictions were difficult to verify, since the methods then available to measure the mass of proteins were inaccurate, such as analytical ultracentrifugation and chemical methods.
Wrinch also predicted that insulin was a C closed cyclol consisting of 288 residues. Limited X-ray crystallographic data were available for insulin which Wrinch interpreted as "confirming" her model. However, this interpretation drew rather severe criticism for being premature. Careful studies of the Patterson diagrams of insulin taken by Dorothy Crowfoot Hodgkin showed that they were roughly consistent with the cyclol model; however, the agreement was not good enough to claim that the cyclol model was confirmed.