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£\-Bungarotoxin (£\-Bgt), a £\-neurotoxin from Taiwan banded krait (Bungarus multicinctus), consists of a single polypeptide chain of 74 amino acid residues cross-linking with five disulfide bonds. In order to explore the structural dependence of the disulfide bonds in the toxin molecule, the mutants with deleting one out of the five disulfide bonds were prepared by site-directed mutagenesis. The mutated and wild-type cDNAs were subcloned into the expression vectors pET14b as well as pET32a(+), and then transformed into Escherichia coli, BL-21(DE3). The recombinant proteins derived from pET14b expression system were isolated from inclusion bodies of E. coli, and refolding into their folded structure in vitro. Alternatively, the proteins derived from pET32a(+) system were expressed as a fusion protein and purified on a His-Bind resin column. Moreover, the recombinant proteins were further purified using a reverse phase column, and the homogeneity of recombinant proteins was determined by SDS-PAGE analyses. Noticeably, the refolding reaction was beneficially achieved by deleting the disulfide bond Cys29-Cys33. Although SDS-PAGE analyses showed that the recombinant proteins were homogeneous in molecular weight, several disulfide isomers appeared in each protein preparation as revealed by native gel analyses. These observations suggest that the formation of disulfide bonds and folding of£\-Bgt may pass through multiple pathways.

There has been lots of research done on customer retention in electronic commerce by using different theories and Model. But there is very less or no work done based on MODE (Motivation and Opportunity as Determinants) model by Fazio 1990. This thesis used MODEL to predict the factors that determine customer in retention in EC. Motivation and opportunity are the most important determinants for consumers choosing an online store. To study motivation and opportunity mechanisms underlying consumer-e-retailer exchange relationship, this research takes a new perspective, a perspective directed toward customer intention to repurchase or customer retention. By integrating MODE model of Fazio 1990 with ¡V process feasibility, switching cost, and relational bond. This study develops an integrated model of consumer retention in an e-retailer. Data for the study was collected using an online survey distributed via email, posting link on the social networking sites linkedin, facebook, and discussion boards¡¦ bbs, NSYSU website. Hypotheses were tested using structural equation modeling of SmartPls. Findings of the study imply that consumer retention in an online store is the affect of consumer motivation towards same online store. Specifically, a consumer¡¦s attitudes toward the key components of his/her entire online purchase experience (i.e., financial bond, social bond, structural bond, time and money saving, and switching cost) constitute the key drivers of consumer retention. Findings also indicate that motivation is intrinsically beneficial. If a consumer motivated by an online store, consumer will come back in the future to repurchase from the same e-retailer. Further, findings suggest that though motivation has a direct effect on future intentions and repurchase. Additionally, findings of the study imply that the effects of motivation on repurchase intention, but the opportunities available from another online store doesn¡¦t affect consumer attitude towards repurchase intention. Moreover search and experience type product moderately affect consumer attitude towards repurchase intention.

Thesis (Ph. D.)--University of Chicago, Dept. of Economics, 2001. / Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--Lehigh University, 2001. / Includes vita. Includes bibliographical references (leaves 185-189).

Thesis (Ph. D.)--University of Missouri-Columbia, 2003. / Typescript. Vita. Includes bibliographical references (leaves 219-228). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2003. / Typescript. Vita. Includes bibliographical references (leaves 219-228). Also available on the Internet.

Rozprawa habilitacyjna--Uniwersytet Warszawski. / Includes bibliographical references (p. [69]-73).

Thesis (Ph. D.)--University of Chicago, Dept. of Economics, August 2001. / Includes bibliographical references. Also available on the Internet.

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