Date of Award


Publication Type

Master Thesis

Degree Name



Biological Sciences

First Advisor

Cotter, D.


Biology, Molecular.



Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.


This research focuses on the activation and deactivation of cysteine proteinases of the cellular slime molds. Cysteine proteinases were isolated from cells of three different life cycles; i.e., the asexual and sexual life cycles of Dictyostelium discoideum, and the asexual life cycle of Polysphondylium pallidum. The cysteine proteinases were separated by gelatin-SDS-Polyacrylamide Gel Electrophoresis. Acid and base treatments of the proteinases in the gels were performed in conjunction with experimental controls. Acid treatments involved exposing the proteinases to 2.7 M acetic acid at pH 2.1 for 60 seconds after electrophoresis. This resulted in an increase in proteolytic activity of the proteinases, and in the appearance of additional proteinases that were not detected in controls. Base treatments involved exposing the proteinases to 1.7 M ammonium chloride at pH 9.5 or greater after acid activation. This revealed a decrease in proteolytic activity of the proteinases compared to acid treatments. Most of the cysteine proteinases isolated from the three life cycles responded similarly to the acid and base treatments. The proteinases also are re-activatable with a second treatment of acetic acid after base deactivation. This supports the hypothesis that activation and deactivation of these proteinases may be due to conformational changes in their protein structure. In addition, E64, an irreversible cysteine proteinase inhibitor, had no affect on acid activation of these proteinases. There are two related hypotheses developed to explain the regulation of these cysteine proteinases with respect to activation and deactivation. (Abstract shortened by UMI.)Dept. of Biological Sciences. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1996 .C38. Source: Masters Abstracts International, Volume: 37-01, page: 0193. Adviser: David A. Cotter. Thesis (M.Sc.)--University of Windsor (Canada), 1996.