Theoretical consideration of the relation between hydrogen bond types and possible secondary structures of a polypeptide chain

An extended set of “secondary structures”, which are defined as systems consisting of the maximum possible number of cooperative units, is considered. The classical and non-classical secondary structures are systematized in a new way. Although it is not assumed that L-stereoisomers of amino acids are preferred in nature, it is shown that such preferences could be imposed when possibilities of spatial rebuilding of the polypeptide chain are limited during a synthesis process.