Daphne Lin Pai

Publication Date


Advisor(s) - Committee Chair

David Hartman Larry Byrd, Martin Houston

Degree Program

Department of Chemistry

Degree Type

Master of Science


Some properties of esterases of the greater wax moth larvae, Galleria mellonela (L.), were examined and the enzymes partially purified. Several buffer systems were tried and it was found that tris buffer was most suitable. The tris buffer resulted in less hydrolysis of the acetylsalicylic acid. Esterase activity was determined with acetylsalicylic acid in tris buffer, pH = 7.85, 0.05 M. The enzymes were partially purified by combination of acetone powder preparations, ammonium sulfate precipitations and gel filtration.

The ratio of esterase activity to protein content was increased 1.03 fold by acetone powder preparation and 1.5 fold by 70% ammonium sulfate precipitation. The ammonium sulfate precipitate in 60-70% was very reproducible. The enzyme showed the greatest instability after 70% ammonium sulfate precipitation; this made further purification difficult. The acetone powder solution was found to be stable at room temperature for about 2 hours.

The pH optimum of esterases was found to be close to 8.0. The esterases were classified as ali-esterases and cholinesterases on the basis of inhibition and activation studies. The enzyme was completely inhibited by 0.05 M veratrine sulfate; 0.001 M mercuric chloride resulted in a 45% inhibition. EDTA increased the activity of the esterases 195% at 0.001 M. This may indicate that there are metal ions in the other tissues of the greater wax moth larvae that are causing inhibition of gut esterases; or, it may indicate that the other tissues contain esterase activity which is sensitive to the presence of metal ions.


Chemistry | Physical Sciences and Mathematics

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