text: Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
  ### Context:
  CREATE TABLE table_name_55 (substrate VARCHAR, product VARCHAR)
  ### Question:
  What is protoporphyrin ix's substrate?
  ### Answer:
  SELECT substrate FROM table_name_55 WHERE product = "protoporphyrin ix"