Question: what is the role of the active site in enzyme catalysed reactions
[{'answer': 'chemical reaction', 'provenance': [{'wikipedia_id': '188688', 'title': 'Active site', 'start_paragraph_id': 1, 'start_character': 100, 'end_paragraph_id': 1, 'end_character': 117, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '188688', 'title': 'Active site', 'start_paragraph_id': 2, 'start_character': 52, 'end_paragraph_id': 2, 'end_character': 688, 'bleu_score': 0.5836448071096481, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 2530762334603513232}, 'section': 'Section::::Abstract.'}]}]