Amino Acid

Is amino acid	Validating whether a residue is an amino acid
Get 1 letter code from name	Translating 3-letter residue codes to single-letter codes
Get standard name	Mapping modified amino acids to standard parent codes
Get expected heavy atoms	Retrieving expected heavy atoms for amino acid residues
Get expected hydrogens	Retrieving expected hydrogens under chemical conditions
Get group db	Inspecting internal residue database records
Get bonded atom pairs	Extracting covalent bonds for amino acid residues