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The free-copper conclusion is drawn from this system and its metallothionein manipulations.\nexposure: CCS deletion, elevated copper, and abrogation of metallothioneins\nevidence_span: {\"source_cache\": \"artifacts/hbot-research/10221913.abstract.txt\", \"locator\": \"Indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"8f6658330988f9b33331f49c1599734e070075a33fa8f32a3a6025d9f0fbc0b8\", \"start_char\": 0, \"end_char\": 1176, \"text_sha256\": \"8f6658330988f9b33331f49c1599734e070075a33fa8f32a3a6025d9f0fbc0b8\"}\n[hbot-p10221913] Undetectable intracellular free copper: the requirement of a copper chaperone for superoxide dismutase. 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