Engineering P450 Peroxygenase to Catalyze Highly Enantioselective Epoxidation of cis-ß-Methylstyrenes.

P450 119 peroxygenase and its site-directed mutants are discovered to catalyze the enantioselective epoxidation of methyl-substituted styrenes. Two new site-directed P450 119 mutants, namely T213Y and T213M, which were designed to improve the enantioselectivity and activity for the epoxidation of styrene and its methyl substituted derivatives, were studied. The T213M mutant is found to be the first engineered P450 peroxygenase that shows highly enantioselective epoxidation of cis-ß-methylstyrenes, with up to 91 % ee. Molecular modeling studies provide insights into the different catalytic activity of the T213M mutant and the T213Y mutant in the epoxidation of cis-ß-methylstyrene. The results of the calculations also contribute to a better understanding of the substrate specificity and configuration control for the regio- and stereoselective peroxygenation catalyzed by the T213M mutant.

Total Synthesis of Chiral Falcarindiol Analogues Using BINOL-Promoted Alkyne Addition to Aldehydes.

An enantioselective total synthesis of chiral falcarindiol analogues from buta-1,3-diyn-1-yltriisopropylsilane is reported. The key step in this synthesis is BINOL-promoted asymmetric diacetylene addition to aldehydes. The two chiral centers of the falcarindiol analogues can be produced by using the same kind of catalyst with high selectivity, and the final product can be obtained in only six steps.

Osteopontin knockdown inhibits αv,ß3 integrin-induced cell migration and invasion and promotes apoptosis of breast cancer cells by inducing autophagy and inactivating the PI3K/Akt/mTOR pathway.

BACKGROUND: Osteopontin (OPN) is associated with tumor formation, progression and metastasis, and increased OPN levels have been associated with poor survival in breast cancer. We investigated the mechanisms responsible for OPN activity, and the relationships between OPN expression and clinical parameters in breast cancer. METHODS: OPN mRNA and protein levels were compared in malignant and benign breast tumors by polymerase chain reaction (PCR) and immunohistochemistry, respectively, and levels in breast cancer cells were determined by PCR and western blotting. The effects of lentiviral-mediated knockdown of OPN on OPN and αv,ß3 integrin expression, cell invasion and migration, autophagy and apoptosis were analyzed in MDA-MB-231 cells. RESULTS: OPN expression increased with aggressiveness of breast cancer phenotype. OPN knockdown inhibited αv,ß3 integrin expression in MDA-MB-231 cells, with subsequent inhibition of cell migration and invasion. Knockdown also inhibited the PI3K/Akt/mTOR pathway, promoted expression of the autophagy-related gene products LC3 and Beclin 1, and increased apoptosis. OPN expression was positively associated with tumor grade and lymph node metastasis. CONCLUSION: These results suggest that knockdown of OPN may inhibit breast cancer metastasis by regulating αv,ß3 integrin expression and inducing autophagy and subsequent inhibition of PI3K/Akt/mTOR signaling, thus providing further insights into the complex mechanisms regulating tumor growth and metastasis.

Tetra-imidazolium piperazinediium bis-(benzene-1,3,5-tricarboxyl-ate) dihydrate.

During the crystallization of the title compound, 4C(3)H(5)N(2) (+)·C(4)H(12)N(2) (+)·2C(9)H(3)O(6) (3-)·2H(2)O, the acidic protons were transferred to the imidazole and piperazine N atoms, forming the final 4:1:2:2 hydrated mixed salt. The mean planes of the three carboxyl-ate groups in the anion are twisted with respect to the the central benzene ring, making dihedral angles of 13.5 (1), 14.5 (1) and 16.9 (1)°. In the crystal, the component ions are linked into a three-dimensional network by a combination of inter-molecular N-H⋯O, O-H⋯O and weak C-H⋯O hydrogen bonds. Further stabilization is provided by π-π stacking inter-actions with centroid-centroid distances of 3.393 (2) Šand weak C=O⋯π inter-actions [O-centroid = 3.363 (2) Å].