The ChemNames module defines several dictionaries of the names, symbols and properties of atoms and compounds. The ChemNames module is located in Yup.Tools. Thus, the required import statement is some variant of: from Yup.Tools.ChemNames import *. This module contains several lists: List Contents Nucleotides Uppercase, single letter code of the standard nucleotides and multi-letter codes of some modified or unusual nucleotides AminoAcids Uppercase, three-letter codes for the twenty standard amino acids StandardResidues Uppercase, three-letter codes for the twenty standard amino acids and single-letter code for the five standard nucleotides. and dictionaries: Dictionary Key Value A1_A3 uppercase three-letter code for the twenty standard amino acids upper case one-letter code A3_A1 uppercase one-letter code for the twenty standard amino acids uppercase three-letter code FULL_A1 uppercase one-letter code for the twenty standard amino acids lower case full name FULL_B1 uppercase one-letter code for the standard bases lower case full name B3_B1 uppercase one-letter code for the five standard bases uppercase three-letter code B1_B3 uppercase three-letter code for the five standard bases uppercase one-letter code MASK_A3B1 three-letter code for the twenty standard amino acids or one-letter code for the five standard bases or two or three-letter codes for modified bases; all codes are uppercase only standard mask value. A3B1_MASK standard mask value three-letter code for the twenty standard amino acids or one-letter code for the five standard bases or two or three-letter codes for modified bases; all codes are uppercase only AtomicMass All keys are uppercase only. Element names; names of extended atoms contain the plus sign, e.g. "O+H" for the OH group; basepairs are prefixed with "#", e.g. "#A" for the A:T basepair, single stranded RNA and other groups are prefixed with "@", e.g. "@PRO" for proline. Atomic or molecular mass. (This dictionary is not complete and many entries contain only placeholder values.) Element Uppercase atom name as found in PDB files. The corresponding uppercase element or extended atom name. (This dictionary is not complete and it returns only element names.) For example: A1_A3["TRP"] yields the value "W". Example >>> from Yup.Tools.ChemNames import * >>> A1_A3["GLU"] 'E' >>> A3_A1["Y"] 'TYR' >>> B3_B1["G"] 'GUA' >>> B1_B3["URA"] 'U' >>> FULL_A1["F"] 'phenylalanine' >>> FULL_B1["C"] 'cytosine' >>> MASK_A3B1["2MG"] 57 >>> A3B1_MASK[19] 'MET' >>> If you want to work in a different case, use the upper() and lower() functions from the Python string module to convert either the key or the value. Atoms AVRecords ChemNames FFA LinSeq MakeLine SwissCheese TraceChain Yup.avf AutoGen Brookhaven Chains Groups MakeGraph ParmTop Topology misc Yup.fpf Yup.scx