code: private static DNASequence getDNASequence(String str) {
  		try {
  			DNASequence s = new DNASequence(str);
  			return s;
  		} catch (CompoundNotFoundException e) {
  
  			logger.error("Unexpected error when creating DNASequence ",e);
  		}
  		return null;
  	}
docs: Returns the DNASequence or null if one can't be created
  @param str
  @return