Crystal structure of neocarzinostatin, an antitumor protein-chromophore complex.
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Kim KH, Kwon BM, Myers AG, Rees DC
Crystal structure of neocarzinostatin, an antitumor protein-chromophore complex.
Science. 1993 Nov 12;262(5136):1042-6.
- PubMed ID
- 8235619 [ View in PubMed]
- Abstract
Structures of the protein-chromophore complex and the apoprotein form of neocarzinostatin were determined at 1.8 angstrom resolution. Neocarzinostatin is composed of a labile chromophore with DNA-cleaving activity and a stabilizing protein. The chromophore displays marked nonlinearity of the triple bonds and is bound noncovalently in a pocket formed by the two protein domains. The chromophore pi-face interacts with the phenyl ring edges of Phe52 and Phe78. The amino sugar and carbonate groups of the chromophore are solvent exposed, whereas the epoxide, acetylene groups, and carbon C-12, the site of nucleophilic thiol addition during chromophore activation, are unexposed. The position of the amino group of the chromophore carbohydrate relative to C-12 supports the idea that the amino group plays a role in thiol activation.