UPV Theses and Dissertations
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Item Acetone -precipitated proteins in cassava (Manihot esculenta Crantz) tubers : Isolation and partial purificationAlbacete, Rose Margaret F. (Division of Physical Sciences and Mathematics, College of Arts and Sciences, University of the Philippines Visayas, 2006-04)Cassava (Manihot esculenta Crantz) is a low-protein starchy staple. In some countries, such as South Africa, cassava bread serves as the major, if not the only, food consumed for a long period of time. This diet causes a disease called protein-energy malnutrition. The total soluble proteins in cassava tubers were extracted using 200 mM Tris- HC1 pH 8.2. Protein fractions were precipitated out at different proportions using acetone (1:1, 1:2, 1:3 crude extract: acetone ratio). Bradford Standard Assay showed that 1:1 crude protein-acetone contained the most amount protein (1.02 x ₋ g/mL protein). This sample and the dialyzed crude sample were both run in gel filtration column in which the eluted fractions generated two peaks each. The highest concentration of the purified protein was 2.67 x 10 5 g/mL protein. The pooled fractions, which made up the peak, were run in SDS-PAGE which revealed bands with molecular weights of 40, 66, 87 and 116 kDa comprised the crude sample (not dialyzed), while the dialyzed sample contained bands with molecular weights of 76 and 87 kDa. The number of proteins decreased after gel filtration.Item Partial purification of pH indicator extracted from Rhoeo spathaceaApa, Junna T. (Department of Chemistry, College of Arts and Sciences, University of the Philippines Visayas, 2009-04)pH test papers are still utilized nowadays despite the prevalence of pH meters, because it is more convenient to use in measuring the pH of a certain substance. The use of natural dye as a pH indicator can serve as a good substitute for an expensive commercial dye that most high schools cannot afford. The pH test papers were prepared by impregnation of 0.03% pure dye extracted from Rhoeo spathacea. TLC was performed to partially remove other plant dye components from the pH active ingredient. The color transition chart was then created at pH ranging from 1.0-13.0 at one unit interval using phosphate buffer. The color transition chart of pure dye extract was compared to the color transition chart of crude dye extract at different pH. Paper impregnated with 0.03% partially purified indicator dye extracted from Rhoeo spathacea showed color transitions from pink to red violet at pH 1.0-3.0; red violet to lavender at pH 3.0-4.0; lavender to blue at pH 4.0-7.0; blue to blue green at pH 7.0-8.0; blue green to green at pH 8.0-11.0; green to yellow green at pH 11.0-12.0; and yellow green to yellow at pH 12.0-13.0. Results also showed that the purified dye extract is a better pH indicator in comparison with the crude dye extract. Spectrophotometric determination of pKa of the indicator was unsuccessful due to the strong overlapping of the UV-Vis spectrum of the acidic and basic forms of the plant dye extract. Titration results showed that the plant indicator can serve as a substitute for the methyl red and phenolphthalein indicators for strong acid-strong base and weak acid-strong base titration, but not for weak acid-weak base titration.