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The adsorption kinetics exhibited by selected charge mutants of T4 lysozyme at silanized silica surfaces were monitored with in situ ellipsometry. Mutant lysozymes were produced by substitution of lysine (Lys) with glutamic acid (Glu). Each substitution resulted in a decrease in the net charge of the protein by 2 units. The wild type lysozyme of net charge +9, and two mutants of net charge +7 and +5 were obtained from E. coli strain RR1 . Adsorption kinetics recorded at hydrophilic and hydrophobic interfaces were compared to the kinetic behavior predicted by two simple models for protein adsorption. One was a three-rate-constant model allowing for reversible adsorption followed by conversion to an irreversibly adsorbed form, and was analyzed under three different conditions. The first condition allowed the adsorption rate (k₁) and the desorption rate (k₋₁) to be variable while the surface-induced conversion rate (s₁) was assumed constant. The second condition assumed k₁ and k₋₁ constant instead of S₁, and the third allowed all kinetic rate constants to be variable. The second model allowed for irreversible adsorption into one of two states directly from solution. Both models suggested that substitution of Lys with Glu in the backbone of T4 lysozyme facilitates the adsorption of the protein at these interfaces. Proteins apparently adsorbed at the interfaces more tightly and occupied a greater interfacial area with substitution of Lys with Glu, and these effects were related to the location of the substitutions relative to other charged residues of the protein, and not to net charge. / Graduation date: 1995

Thesis (M.S.)--Youngstown State University, 2007. / Includes bibliographical references (leaves 40-41). Also available via the World Wide Web in PDF format.

Thesis (Ph. D.)--Illinois State University, 1985. / Title from title page screen, viewed July 6, 2005. Dissertation Committee: Brian J. Wilkinson (chair), David P. Brunner, Mathew J. Nadakavukaren, Robert L. Preston, Arlan G. Richardson. Includes bibliographical references (leaves 178-192) and abstract. Also available in print.

Thesis (M.S.)--University of Wisconsin--Madison, 1968. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

University, Diss., 2006--Würzburg.

nÃo hà / As infecÃÃes entÃricas causam cerca de 2,5 milhÃes de mortes ao ano. A EAEC està associada à causa de doenÃas diarrÃicas persistentes. Este estudo analisou in vitro (IEC-6, Caco-2 e HEp-2), o papel dos micronutrientes glutamina, alanil-glutamina, Ã-caroteno, zinco, e dos leites de cabra transgÃnico com lisozima humana e controle nos ensaios de proliferaÃÃo, migraÃÃo, viabilidade, apoptose, necrose celular, adesÃo bacteriana em resposta à infecÃÃo causada pela cepa de EAEC-042 na concentraÃÃo de 2,5 x 105 UFC/mL. A cepa bacteriana de EAEC-042 mostrou reduÃÃo significativa na migraÃÃo (p<0,001) e na viabilidade celular (p<0,001) e esta aumentou a apoptose (p<0,001) e necrose (p<0,001) em resposta a lesÃo ao epitÃlio intestinal. Foi observado que os micronutrientes na presenÃa da bactÃria reduziram significativamente a apoptose e necrose ocasionados por esta, bem como reduziram significativamente a adesÃo bacteriana, alÃm de aumentar a migraÃÃo celular. Os leites controle e transgÃnico apresentaram reduÃÃo significativa da adesÃo bacteriana (p<0,001), independente da presenÃa da camada de gordura, alÃm de reduzirem significativamente a apoptose (p<0,001) e a necrose (p<0,001) ocasionadas pela EAEC-042. A anÃlise qualitativa de aderÃncia celular, considerada padrÃo ouro, mostrou reduÃÃo na aderÃncia bacteriana quando associados aos micronutrientes, comparados ao controle com EAEC-042. Nota-se a quase ausÃncia de aderÃncia em ambos os leites. Este estudo mostra a importÃncia dos micronutrientes e leite de cabra transgÃnico ou nÃo, sobre a proteÃÃo epitelial intestinal nas agressÃes bacterianas. / The enteric infections cause 2.5 million deaths each year. The Enteroaggregative Escherichia coli (EAEC) is associated with persistent cause of diarrheal diseases. This study examined in vitro (IEC-6, Caco-2 and HEp-2 cells) the role of the micronutrients glutamine (Glu), alanyl-glutamine (Ala-Glu), beta-carotene (Ã-Carot), zinc (Zn), and the milk of transgenic goats containning human lysozyme (M-Lyso) and their respective controls (Ctrle) in the following assays: proliferation, migration, viability, apoptosis, cell necrosis, and bacterial adhesion in response to infection caused by the EAEC-042 bacterial strain at a concentration of 2.5 x 105 CFU/mL. The effect of infection by EAEC-042 bacterial strain was evidenced by significant reduction in migration (p <0.001) and cellular viability (p <0.001); also increased apoptosis (p <0.001) and necrosis (p <0.001) in response to damage to the intestinal epithelium. It was observed that the micronutrients in the presence of bacteria significantly reduced apoptosis and necrosis caused by EAEC-042, as well as significantly reduced bacterial adhesion and increases cell migration. The control and transgenic milk abolished bacterial adhesion (p <0.001), independent of milk fat, and significantly reduce apoptosis (p <0.001) and necrosis (p <0.001) caused by EAEC-042. The qualitative analysis of EAEC adherence, considered as gold standard method, showed a reduction in bacterial adherence associated with intervention with micronutrients when compared with the EAEC-042 infection control. In conclusion, our study demonstrates the importance of intervention with micronutrients and milk (transgenic or not) in protecting the intestinal epithelial challenged by bacterial aggression.