- Remarkable electronic and steric effects in the nitrile biotransformations for the preparation of enantiopure functionalized carboxylic acids and amides: Implication for an unsaturated carbon-carbon bond binding domain of the amidase
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(Chemical Equation Presented) Biotransformations of various functionalized racemic nitriles catalyzed by Rhodococcus erythropolis AJ270, a nitrile hydratase/amidase-containing microbial whole-cell catalyst, were studied. While the nitrile hydratase exhibi
- Gao, Ming,Wang, De-Xian,Zheng, Qi-Yu,Huang, Zhi-Tang,Wang, Mei-Xiang
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p. 6060 - 6066
(2008/02/10)
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- Design, synthesis, and structure-activity relationships of haloenol lactones: Site-directed and isozyme-selective glutathione S-transferase inhibitors
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Overexpression of glutathione S-transferase (GST), particularly the GST-π isozyme, has been proposed to be one of the biochemical mechanisms responsible for drug resistance in cancer chemotherapy, and inhibition of overexpressed GST has been suggested as an approach to combat GST-induced drug resistance. 3-Cinnamyl-5(E)-bromomethylidenetetrahydro-2-furanone (1a), a lead compound of site-directed GST-π inactivator, has been shown to potentiate the cytotoxic effect of cisplatin on tumor cells. As an initial step to develop more potent and more selective haloenol lactone inactivators of GST-π, we examined the relationship between the chemical structures of haloenol lactone derivatives and their GST inhibitory activity. A total of 16 haloenol lactone derivatives were synthesized to probe the effects of (1) halogen electronegativity, (2) electron density of aromatic rings, (3) molecular size and rigidity, (4) lipophilicity, and (5) aromaticity on the potency of GST-π inactivation. The inhibitory potency of each compound was determined by time-dependent inhibition tests, and recombinant human GST-π was used to determine their inhibitory activity. Our structure-activity relationship studies demonstrated that (1) reactivity of the halide leaving group plays a weak role in GST inactivation by the haloenol lactones, (2) aromatic electron density may have some influence on the potency of GST inactivation, (3) high rigidity likely disfavors enzyme inhibition, (4) lipophilicity is inversely proportional to enzyme inactivation, and (5) an unsaturated system may be important for enzyme inhibition. This work facilitated understanding of the interaction of GST-π with haloenol lactone derivatives as site-directed and isozyme-selective inactivators, possibly potentiating cancer chemotherapy.
- Wu, Zhixing,Minhas, Gurpreet Singh,Wen, Dingyi,Jiang, Hualiang,Chen, Kaixian,Zimniak, Piotr,Zheng, Jiang
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p. 3282 - 3294
(2007/10/03)
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- A novel type of structurally simple nonpeptide inhibitors for α- chymotrypsin. Induced-fit binding of methyl 2-allyl-3-benzene-propanoate to the S2 subsite pocket
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Unexpectedly, methyl and benzyl esters of 2-allyl-3-benzenepropanoic acid were found to be not substrates but potent competitive inhibitors for α-chymotrypsin. The inhibitory property of the structurally simple nonpeptidic compounds is ascribed to their high binding affinity to the enzyme at the S2 rather than S1 subsite pocket. These inhibitors exist in a flexible form in solution, but as they bind to the enzyme bulky contrained conformers present in a minute concentration play an important role, forming tighter enzyme-inhibitor complexes by binding to the large hydrophobic S2 pocket. The contrained conformers are thought to be resulted from intramolecular CH/π interactions between a vinylic proton and the aromatic π-electron cloud in the inhibitor molecules. These compounds constitute novel examples of the induced-fit binding inhibitor of possibly simplest structure.
- Kim, Dong H.,Li, Zhi-Hong,Lee, Soo Suk,Park, Jeong-Il,Chung, Sang J.
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p. 239 - 249
(2007/10/03)
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