With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: Vanilla Sky stars a former American fashion model.
text_B: In enzymology , a peptide-tryptophan 2,3-dioxygenase is an enzyme that catalyzes the chemical reaction. enzymology. enzymology. enzyme. enzyme. catalyzes. catalysis. chemical reaction. chemical reaction. peptide tryptophan + O2 peptide formylkynurenine. peptide tryptophan. peptide tryptophan. peptide formylkynurenine. peptide formylkynurenine. Thus , the two substrates of this enzyme are peptide tryptophan and O2 , whereas its product is peptide formylkynurenine .. enzyme. enzyme. substrates. substrate ( biochemistry ). peptide tryptophan. peptide tryptophan. product. product ( chemistry ). peptide formylkynurenine. peptide formylkynurenine. This enzyme belongs to the family of oxidoreductases , specifically those acting on single donors with O2 as oxidant and incorporation of two atoms of oxygen into the substrate -LRB- oxygenases -RRB- .. enzyme. enzyme. The oxygen incorporated need not be derived from O2 .. The systematic name of this enzyme class is peptide-tryptophan  : oxygen 2,3-oxidoreductase -LRB- decyclizing -RRB- .. enzyme. enzyme. oxidoreductase. oxidoreductase. systematic name. List of enzymes. Other names in common use include pyrrolooxygenase , peptidyltryptophan 2,3-dioxygenase , and tryptophan pyrrolooxygenase .
not_related.