code: public static String convertOneLetterCodeToThreeLetterCode(String oneLetterCode) {
          AminoAcid[] monomers = createAAs();
          for (int i = 0; i < monomers.length; i++) {
              if (monomers[i].getProperty(RESIDUE_NAME_SHORT).equals(oneLetterCode)) {
                  return (String) monomers[i].getProperty(RESIDUE_NAME);
              }
          }
          return null;
      }
docs: Returns the three letter code of an amino acid given a one letter code.
  For example, it will return "Val" when "V" was passed.