Diss. (sammanfattning) Linköping : Linköpings universitet, 2005. / Härtill 4 uppsatser.

A thesis submitted to the Faculty of Science, University of the Witwatersrand, in fulfilment of the requirements for the degree of Doctor of Philosophy. / A glutathione S-transferase (Sj26GST) from Schistosoma japonicum, which functions in the parasite's Phase II detoxification pathway, is expressed by the Pharmacia pGEX-2T plasmid and is widely used as a fusion-protein affinity tag. It contains all 217 residues of Sj26GST and an ad titional 9-residue peptide linker with a thrombin cleavage site at its C-terminus. Size-exclusion HPLC (SEC-HPLC) and SDS-PAGE studies indicate that purification of the homodimeric protein under nonreducing conditions results in the reversible for-ration of significant amounts of 160 -kDa and larger aggregates without a loss in catalytic activity. The basis for oxidative aggregation can be ascribed to the high degree of exposure of the four cysteine residues per subunit. The conformational stability of the dimeric protein was studied by urea- and temperature-induced unfolding techniques. Fluorescence-spectroscopy, SEC-HPLC, urea- and temperature-gradient gel electrophoresis, ultraviolet melting, differential scanning micro calorimetry , and enzyme activity were employed to monitor structural and functional changes. The unfolding data indicate the absence of thermodynamically stable intermediates and that the umolding/refolding transition is a two-state process involving folded native dimer and unfolded monomer. The stability of the protein was found to be dependent on its concentration with a ~GO(H20) = 26 ±1.7 kcal/mol. The conformational stability was unchanged in the presence of the leading antischistosomal drug Praziquantel, which bound the protein with a Kd = 9 ±1.8 p,M. The strong relationship observed between the m-v,llue and the size of the protein indicates that the amount of protem. surface exposed to solvent upon unfolding is the major structural de.erminant for the dependence of the protein's free energy of unfolding on urea concentration. 'Ihermograms obtained by differential scanning calorimetry also fitted to a two-state irreversible unfolding transition, both in the presence and absence of Praziquantel, with values of ~Cp = 1779 cal mol-IK-I , ~HcaI = 227 kcal/mol, AHVH ::::::233 kcal/mol (r :::::~:HVHIAlIcal = 1.02) and AS = 354 cal mol''K". The low ~Cp and ~S, when compared with the theoretically determined values, implied that the thermal denaturation of Sj26GST did not result in complete unfolding of the protein, / Andrew Chakane 2018

by Yuen Wai Keung. / Thesis submitted in: December 1999. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (leaves 99-112). / Abstracts in English and Chinese. / Acknowledgement --- p.i / Abstract --- p.ii / Abstract (Chinese Version) --- p.iv / Abbreviations --- p.vi / Table of Contents --- p.viii / Chapter chapter one --- introduction --- p.1 / Chapter 1.1 --- Glutathione S-transferase --- p.2 / Chapter 1.1.1 --- Introduction --- p.2 / Chapter 1.1.2 --- Classification of mammalian GST --- p.2 / Chapter 1.1.3 --- Classification of insect GST --- p.7 / Chapter 1.1.4 --- Substrate specificity --- p.11 / Chapter 1.2 --- The chironomidae --- p.13 / Chapter 1.2.1 --- Biology and life history of chironomidae --- p.13 / Chapter 1.3 --- Chironomidae larvae --- p.16 / Chapter 1.3.1 --- Bloodworm t --- p.6 / Chapter 1.3.2 --- Sources of chironomidae larvae --- p.17 / Chapter 1.4 --- Aim of research --- p.18 / Chapter chapter two --- materials and methods --- p.20 / Chapter 2.1 --- Screening of GST in different subcellular fractions --- p.21 / Chapter 2.1.1 --- Preparation of mitochondria --- p.21 / Chapter 2.1.2 --- Preparation of microsomes --- p.22 / Chapter 2.1.3 --- Preparation of cytosol --- p.22 / Chapter 2.2 --- Assay for GST activity --- p.23 / Chapter 2.2.1 --- Activity Units --- p.23 / Chapter 2.3 --- Protein assay --- p.23 / Chapter 2.4 --- Preparation of glutathione-affinity column --- p.25 / Chapter 2.5 --- Purification of cytosolic GSTs --- p.26 / Chapter 2.5.1 --- Preparation of cytosol --- p.26 / Chapter 2.5.2 --- Chromatography on Sephadex G25 --- p.26 / Chapter 2.5.3 --- Affinity Chromatography --- p.26 / Chapter 2.5.3.1 --- Specific elution of GSTs --- p.26 / Chapter 2.5.3.2 --- Non-specific elution of GSTs --- p.27 / Chapter 2.5.4 --- Fast Protein Liquid Chromatography with Mono Q --- p.27 / Chapter 2.6 --- Determination of molecular mass --- p.29 / Chapter 2.6.1 --- Subunit molecular mass --- p.29 / Chapter 2.6.2 --- Native molecular mass --- p.31 / Chapter 2.7 --- Isoelectric focusing PAGE --- p.31 / Chapter 2.8 --- Enzyme activities and kinetic studies --- p.34 / Chapter 2.8.1 --- Optimum pH --- p.34 / Chapter 2.8.2 --- Heat inactivation assay --- p.34 / Chapter 2.8.3 --- Km and Vmax --- p.34 / Chapter 2.8.4 --- Substrate specificity --- p.35 / Chapter 2.8.5 --- Glutathione peroxidase activity --- p.38 / Chapter 2.9 --- N-terminal amino acid sequence analysis --- p.39 / Chapter 2.9.1 --- Semidry electroblotting --- p.39 / Chapter 2.9.2 --- Staining of proteins on PVDF membrane --- p.40 / Chapter 2.9.3 --- N-terminal amino acid sequence analysis --- p.40 / Chapter 2.9.4 --- On-membrane deblocking of protein --- p.40 / Chapter 2.9.5 --- BLAST search --- p.41 / Chapter chapter three --- results --- p.42 / Chapter 3.1 --- Screening of GST in different subcellular fractions --- p.43 / Chapter 3.2 --- Purification of cytosolic GSTs by chromatography --- p.45 / Chapter 3.2.1 --- Sephadex G25 column --- p.45 / Chapter 3.2.2 --- GSH affinity column --- p.45 / Chapter 3.2.3 --- Mono-Q column --- p.45 / Chapter 3.3 --- Determination of molecular mass --- p.53 / Chapter 3.3.1 --- Subunit molecular mass --- p.53 / Chapter 3.3.2 --- Native molecular mass --- p.53 / Chapter 3.4 --- Isoelectric point determination --- p.53 / Chapter 3.5 --- Enzymes activities and kinetic studies --- p.57 / Chapter 3.5.1 --- Optimum pH --- p.57 / Chapter 3.5.2 --- Thermostability --- p.57 / Chapter 3.5.3 --- Km and Vmax --- p.57 / Chapter 3.5.4 --- Substrate specificity --- p.76 / Chapter 3.5.5 --- Glutathione peroxidase Activity --- p.76 / Chapter 3.6 --- N-terminal amino acid sequence analysis --- p.83 / Chapter chapter four --- discussion --- p.89 / Chapter 4.1 --- GST in different subcellular fractions --- p.90 / Chapter 4.2 --- Purification of cytosolic GST --- p.91 / Chapter 4.3 --- Physical properties --- p.93 / Chapter 4.3.1 --- Subunit molecular mass --- p.93 / Chapter 4.3.2 --- Native molecular mass --- p.93 / Chapter 4.3.3 --- Isoelectric point --- p.95 / Chapter 4.4 --- Kinetic properties --- p.94 / Chapter 4.4.1 --- Optimum pH --- p.94 / Chapter 4.4.2 --- Thermostability --- p.95 / Chapter 4.4.3 --- Km and Vmax --- p.95 / Chapter 4.4.4 --- Substrate specificity --- p.96 / Chapter 4.4.5 --- Glutathione peroxidase activity --- p.96 / Chapter 4.5 --- N-terminal amino acid sequence data --- p.97 / Chapter 4.6 --- Conclusion --- p.98 / references --- p.99

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 91-106).

Background and Objective: Severe inflammation resulted from small-for-size liver graft injury provides favorable environment for tumor growth. The oxidative stress not only accelerates the inflammatory response, but also stimulates the proliferation of cancer cells. Therefore, attenuating oxidative stress after liver surgery may not only ameliorate liver injury, but also suppress tumor growth and metastasis. Glutathione peroxidase 3 (GPx3) is an anti-oxidant which has been reported to be down-regulated in several types of cancer. Here, we aimed to investigate the clinical significance of GPx3 and characterize the role of GPx3 in liver graft injury and hepatocellular carcinoma (HCC). Furthermore, we intended to explore the therapeutic value of GPx3 using hiPSC-MSCs as a delivery vehicle in hepatic ischemia-reperfusion injury and HCC. Materials and methods: To investigate the clinical significance of GPx3, the HCC patients underwent liver transplantation (106 recipients) or hepatectomy (113 patients) were recruited to study the correlation of GPx3 with clinical parameters. To explore the mechanism of GPx3 in liver graft injury, simulated IR injury model and rat liver transplantation model were applied. To examine the effect of GPx3 on HCC, rGPx3 administration and forced-expression of GPx3 within HCC cells were performed in vitro and in vivo. To explore the therapeutic value of GPx3, engineered hiPSC-MSCs delivering GPx3 was established and applied in mice hepatic IR injury model and nude mice liver cancer model. Results: I. The role of GPx3 in graft injury. The intra-graft GPx3 expression was significantly down-regulated in small-for-size graft accompanied with severe graft injury in a rat liver transplantation model. Clinically, the lower plasma GPx3 was mainly observed in the recipients with small-for-size liver graft. Furthermore, the lower plasma GPx3 significantly correlated with higher tumor recurrence post-transplantation. The down-regulation of GPx3 was associated with hepatic senescence in small-for-size graft. GPx3 treatment delivered by hiPSC-MSCs could significantly ameliorated hepatic IR injury through inhibition of macrophages activation followed by decreased production of ROS, TNFα and IL-1. II. The role of GPx3 in HCC. Down-regulation of GPx3 in liver tumor was observed in half of HCC patients (56/113). It significantly correlated with advanced pTNM stage (P = 0.024), presence of venous infiltration (P =0.043) and high AFP level (P = 0.006). The one year (P = 0.038) and five year (P = 0.019) recurrence rate were significantly higher in the patients with lower GPx3 expression. In functional study, rGPx3 administration and over-expression of GPx3 significantly suppressed proliferation and invasiveness of HCC cells in vitro and in vivo. The tumor suppressive activity of GPx3 was mediated by inhibition of EMT through Erk-NFκB-SIP1 pathway. The GPx3 treatment delivered by hiPSC-MSCs could significantly inhibit proliferation of MHCC97L. Conclusions: I. Down-regulation of GPx3 was associated with small-for-size graft injury. Low circulating GPx3 at early phase after transplantation predicted higher tumor recurrence of HCC recipients. II. Down-regulation of GPx3 indicated poor prognosis of HCC patients. GPx3 suppressed tumor growth and invasiveness by inhibition of EMT through Erk-NFκB-SIP1 pathway. III. Engineered hiPSC-MSCs delivering GPx3 may possess therapeutic value in liver graft injury and HCC. / published_or_final_version / Surgery / Doctoral / Doctor of Philosophy

Diss. (sammanfattning) Uppsala : Univ., 2002. / Härtill 6 uppsatser.

Thesis (Ph. D.)--University of Washington, 1998. / Vita. Includes bibliographical references (leaves [48]-59).

Thesis (M.S.)--Brandeis University, 2009. / Title from PDF title page (viewed on June 29, 2009). Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 1999. / Vita. Includes bibliographical references (leaves 107-130).

Thesis (Ph. D.)--West Virginia University, 2008. / Title from document title page. Document formatted into pages; contains xi, 109 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 92-109).