CHUCKLES: A method for representing and searching peptide and peptoid sequences on both monomer and atomic levels

Dual representation of peptide and non-peptide structures in a chemical database as atomic-level molecular graphs and sequence strings permits chemical substructure and similarity searches as well as sequence-based substring and regular expression searches. CHUCKLES interconverts monomer-based sequences with SMILES, which represent atomic-level molecular graphs. Forward-translation maps peptide or other sequences into SMILES. Back-translation extracts monomer sequences from SMILES. This approach permits a generalized representation of monomers allowing user specification of any monomer. CHUCKLES allows mixing of atoms with user-defined monomer names; that is, monomer representation is consistent with SMILES notation. In addition, oligomer branching and cyclization are handled.