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A Comparative Analysis Of Hydrolysis Kinetics By Spla2 Isoforms During Apoptosis In S49 Cells, Erin Dalene Olson
A Comparative Analysis Of Hydrolysis Kinetics By Spla2 Isoforms During Apoptosis In S49 Cells, Erin Dalene Olson
Theses and Dissertations
Secretory Phospholipase A2 (sPLA2) represents a diverse class of roughly 20 enzymes, 12 of which have been identified in humans. These isoforms can be distinguished based on their tissue distribution, structure, and regulation. These differences in structure between the isoforms lead to the question does the enzyme's ability to respond to physical changes in the membrane during apoptosis governed by structure. S49 cell apoptosis was initiated by treatment with either the glucocorticoid dexamethasone (6–48 h) or with the calcium ionophore, ionomycin. The rates of hydrolysis were compared with each treatment condition for various concentrations of snake venom and human groups …
Mechanisms By Which Apoptotic Membranes Become Susceptible To Secretory Phospholipase A2, Rachel Williams Bailey
Mechanisms By Which Apoptotic Membranes Become Susceptible To Secretory Phospholipase A2, Rachel Williams Bailey
Theses and Dissertations
During apoptosis, changes occur in T-lymphocyte membranes that render them susceptible to hydrolysis by secretory phospholipase A2 (sPLA2). To study the relevant mechanisms, a simplified model of apoptosis using a calcium ionophore was first applied. Kinetic and flow cytometry experiments provided key observations regarding ionophore treatment: initial hydrolysis rate was elevated, total reaction product was increased four-fold, and adsorption of the enzyme to the membrane surface was unaltered. Analysis of these results suggested that susceptibility during calcium-induced apoptosis is limited by substrate availability rather than enzyme adsorption. Fluorescence experiments identified three membrane alterations that might affect substrate access to the …