Structural Basis for Chloroperoxidase Catalyzed Enantioselective Epoxidations and Mechanisms of Selected Anticancer Drug Induced Apoptosis

Chloroperoxidase (CPO), a member of the heme peroxidase family, has diverse catalytic activities toward a broad range of substrates. In addition to catalyzing halogenation reactions involved in the biosynthesis of halogen-containing compounds, CPO also catalyzes reactions typical of traditional heme peroxidases, catalases, and cytochrome P450 enzymes. Despite the powerful and versatile catalytic activity of CPO, its applications have been thwarted by the difficulty in regenerating the active enzyme and substrate (peroxide) induced protein inactivation. To overcome these shorting comings of the protein, we investigate the fabrication and characterization of chloroperoxidase (CPO) and glucose oxidase (GOx) on the surface of MGO. The performance of the immobilized CPO was considerably enhanced by coupling with GOx that provided the required H2O2 in situ through glucose oxidation. The activity of MGO-GOx-CPO (96.6%) towards the decolorization of orange G was much superior to that of MGO-GOx+MGO-CPO (86.2%), probably as a result of reduced mass transfer resistance between CPO and H2O2 generated from GOx molecules. MGO-GOx-CPO can be conveniently reused for its ease of recovery in the presence of an external magnetic field, with ∼38.5% activity remained after 6 cycles of applications. The work detailed in Chapter 2 of this dissertation demonstrates the feasibility of co-immobilizing CPO and GOx onto MGO and the potential of MGO-GOx-CPO in environmental applications.The versatility of CPO has long been attributed to the unique structural components of the protein environment that constitute the heme active site, particularly the identity of the axial heme ligand and amino acid residues distal to the heme iron. The heme active site structure has also been thought to be responsible for the enantioselectivity of CPO. Chapter 3 of my dissertation investigates the structural factors that contribute to CPO’s stereoselectivity in catalyzing epoxidation reactions. The characterization of CPO-substrate complex will be carried out using UV-Vis spectrophotometry and nuclear magnetic resonance (NMR) spectroscopy. We will focus on understanding the mechanism of CPO-catalyzed enantioselective epoxidation and structure-activity relationship of CPO. Non-small-cell lung carcinoma (NSCLC) continues to be a vital human healthcare problem worldwide for its high incidence and consequent mortality rate. In this study, we investigated the anticancer effect of LZ-101, a novel derivative of danofloxacin, against non-small-cell lung cancer and the underlying mechanisms. In vitro, LZ-101 inhibited the viability of A549 human non-small cell lung cancer cells. We demonstrated that LZ-101 induced mitochondrial-mediated apoptosis by increasing Bax/Bcl-2 ratio, loss of mitochondrial membrane potential (ΔΨm), cytochrome c (Cyt c) release and apoptosis-inducing factor (AIF) transposition in A549 cells. Further research illuminated that LZ-101 induced apoptosis was related to the activation of FOXO3a/Bim pathway. Moreover, we found that LZ-101 increased the stability of FOXO3a by blocking autophagy-dependent FOXO3a degradation. In vivo, LZ-101 exerted a remarkable antitumor activity with high safety in xenograft model inoculated A549 tumor through the same mechanism as in our in vitro study. Our findings indicated that LZ-101 induces mitochondrial apoptosis and stabilizes FOXO3a by blocking autophagy flux. Enhanced energy metabolism plays important roles in the growth and survival of cancer cells. Here, we investigated the mechanisms of a newly synthesized flavonoid, GL-V9, in the inhibition of glycolysis and the induction of apoptosis of human breast cancer cell lines MDA-MB-231 and MCF-7 cells. We find that hexokinase II (HKII) plays important roles in the anticancer effects of GL-V9. GL-V9 not only downregulate the expression of HKII in MDA-MB-231 and MCF-7 cells, but also induce dissociation of HKII from voltage-dependent anion channel (VDAC) in mitochondria, resulting in glycolytic inhibition and mitochondrial-mediated apoptosis. The dissociation of HKII from mitochondria is attributed to GSK-3β-induced phosphorylation of mitochondrial VDAC. Our in vivo experiments also show that GL-V9 significantly inhibits the growth of human breast cancer due to activation of GSK-3β and inactivation of AKT. Thus, GL-V9 induces cytotoxicity via regulation of HKII binding to mitochondria. Our work demonstrates the significance of metabolic regulator in cancer growth and offers fresh insight into the molecular basis for the development of flavonoid as novel agents for the treatment of breast carcinoma

LZ-101, a novel derivative of danofloxacin, induces mitochondrial apoptosis by stabilizing FOXO3a via blocking autophagy flux in NSCLC cells

Non-small-cell lung carcinoma (NSCLC) continues to be a vital disease worldwide for its high incidence and consequent mortality rate. In this study, we investigated the anti-cancer effect of LZ-101, a new derivative of danofloxacin, against non-small-cell lung cancer and the underlying mechanisms. In vitro, LZ-101 inhibited the viability of human non-small cell lung cancer cell lines. We demonstrated that LZ-101 induced mitochondrial-mediated apoptosis by increasing Bax/Bcl-2 ratio, loss of mitochondrial membrane potential (ΔΨm), release of cytochrome c (Cyt c) and apoptosis-inducing factor (AIF) in A549 cells. Further research illuminated that LZ-101 induced apoptosis was related to the activation of FOXO3a/Bim pathway. Moreover, we found that LZ-101 increased the stability of FOXO3a by blocking autophagy-dependent FOXO3a degradation. However, inhibition of autophagosome formation abolished FOXO3a stabilization and apoptosis induced by LZ-101. In vivo, LZ-101 exerted a remarkable anti-tumor activity with high safety in xenograft model inoculated A549 tumor through the same mechanism as in our in vitro study. In conclusion, our findings indicated that LZ-101 induces mitochondrial apoptosis and stabilizes FOXO3a by blocking autophagy flux

A quantum circuit simulator and its applications on Sunway TaihuLight supercomputer

Classical simulation of quantum computation is vital for verifying quantum devices and assessing quantum algorithms. We present a new quantum circuit simulator developed on the Sunway TaihuLight supercomputer. Compared with other simulators, the present one is distinguished in two aspects. First, our simulator is more versatile. The simulator consists of three mutually independent parts to compute the full, partial and single amplitudes of a quantum state with different methods. It has the function of emulating the effect of noise and support more kinds of quantum operations. Second, our simulator is of high efficiency. The simulator is designed in a two-level parallel structure to be implemented efficiently on the distributed many-core Sunway TaihuLight supercomputer. Random quantum circuits can be simulated with 40, 75 and 200 qubits on the full, partial and single amplitude, respectively. As illustrative applications of the simulator, we present a quantum fast Poisson solver and an algorithm for quantum arithmetic of evaluating transcendental functions. Our simulator is expected to have broader applications in developing quantum algorithms in various fields.Comment: 21 pages, 9 figure