 At a 1933 lecture by Astbury to the Oxford Junior Scientific Society, physicist Frederick Frank suggested that the fibrous protein α-keratin might be stabilized by an alternative mechanism, namely, "covalent" crosslinking of the peptide bonds by the cyclol reaction above.The cyclol crosslink draws the two peptide groups close together; the N and C atoms are separated by ~1.5 Å, whereas they are separated by ~3 Å in a typical hydrogen bond.The idea intrigued J. D. Bernal, who suggested it to the mathematician Dorothy Wrinch as possibly useful in understanding protein structure.