Chemical Aspects of the Cyclol Hypothesis

Abstract

CONSIDERABLE discussion of the structure of proteins, especially in relation to the cyclol hypothesis, has recently appeared in NATURE^1,2,3. This theory assumes that globular proteins consist of a spaceenclosing arrangement of diazine and triazine rings. Most of the evidence produced (including the X-ray diagrams^2,3) is, however, not specific for the cyclol theory; many of the points made by Langmuir⁴ could be equally well used as an argument in favour of any regular geometrical structure which joins peptide chains to form a globular molecule. It is indeed possible to suggest bonds between peptide chains of types already known to exist; thus we are familiar with compounds containing the linkages S—S; CO—S, NH—S or CO—NH—CO, all of which might occur in proteins; in addition, the possibility exists of linkages between hydroxyl groups of hydroxy-amino acids and free carboxyl groups.