Neocarzinostatin (NCS) is a macromolecular chromoprotein enediyne antitumor antibiotic secreted by Streptomyces macromomyceticus.
It consists of two parts, a labile chromophore (the non-protein molecular entity shown at right) and a 113 amino acid protein to which the chromophore is tightly and non-covalently bound with high affinity (Kd ~ 10−10 M). [Source: Wikipedia 
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