Browsing by Author "Acquaah, R.A."
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Item Extraction, Purification And Partial Characterization Of The Sweet Modifying Glycoprotein, Miraculin From Richardella Dulcifica(University of Ghana, 1996-04) Achel, D.G.; Acquaah, R.A.; Armah, G.E.; University of Ghana, College of Basic and Applied Sciences, School of Biological Sciences, Department of Biochemistry, Cell and Molecular BiologyIn the present study miraculin, a non-nutritive taste modifier from the tropical plant, Richardella dulcifica has been purified to homogeneity. It was extracted from the pulp of the fruits in 0.5M NaCl and purified at ordinary temperatures by a three step chromatographic process namely; Hydrophobic interaction chromatography, (HIC), Ion exchange chromatography, (IEC), and Gel filtration chromatography (GFC) respectively. The relative molecular weight (Mr) of purified miraculin was about 43, 000 and 100 fig/ml of the lyophilized product provoked sweetness with lemon. N-terminal amino acid analysis revealed two forms of miraculin, the major form being more than 70 % of the total miraculin population. Protease activity was detected and measured in the pulp of fresh and aged fruits. The activity .and specific protease activity in the pulp of freshly picked berries were 0.0756 units/mg pulp and 0.2414 units/mg protein respectively. Corresponding values for the aged (at least six months old) berries were 0.0369 unit/mg pulp and 0.1342 unit/mg protein. The difference was significant (p s 0.05) . Total protein content measured for the fresh and aged berries were 31.3% + 1.9% and 27.4% + 0.3% (w/w) respectively. The difference was not significant (p <; 0.05), in addition only approximately 10 % (w/w) of the fruits contained the active principle, miraculin. A predictive model: Z = 0.027348 - 0.015177^ - 0.003364/tpH + 0.000128pH + 0.029960/i2 where Z is the solubility, was developed to explain the effect of ionic strength (/x) and pH on the solubility of miraculin. The model had an R2 Of 66.12%. Analysis of variance (ANOVA) showed ionic strength to be the most influential variable in the model. The protein had the maximum solubility at low pH and low ionic strength, with the minimum solubility recorded at high pH and high ionic strength. A thermal denaturation investigation, established that water-glycerol mixtures substantially increased the melting temperature of the purified product.Item Methionine Metabolism in Filarial Worms(University of Ghana, 1980-09) Acquaah, R.A.; Oduro, K.K.; Jaffe, J.J.; Gyang, F.N.; University of Ghana, College of Basic and Applied Sciences, School of Biological Sciences, Department of Biochemistry, Cell and Molecular BiologyAdult filariae apparently lack the vitamin BI2-dependent and -independent methyltransferases for the de novo synthesis of methionine and seem to meet their requirement of this amino acid from an exogenous source and the activity of S-adenosylmethionine(AdoMet):homocysteine S-methyltransferase The properties of filarial AdoMet:homocysteine methyl transferase were similar to the analogous microbial enzyme. However, adult filariae possess the enzymatic capability to metabolize methionine to cyst(e)ine. When incubated in the presence of L-{CH3-14C} methionine to induce them to synthesise AdoMet, adult Dirofilaria immitis incorporated the radiolabel into phospholipid and protein fractions. The significance of filarial methionine metabolism especially with regard to its suitability as a potential target for antifilarial chemotherapy is discussed.Item Molecular Analysis of the Genomic Dna of Six Varieties of Cowpea, Vigna Unguiculata L. Walp(University of Ghana, 1996-09) Crabbe, E.; Wilson, M.D.; Acquaah, R.A.; University of Ghana, College of Basic and Applied Sciences, School of Biological Sciences, Department of Biochemistry, Cell and Molecular BiologyThree non-chemical conditions of preservation, storage at room temperature (that is benchtop), in a freezer and at simulated herbarium were examined to determine which is most suitable for the preservation of cowpea leaves for molecular studies. Under each storage condition, the effect of duration of storage and the difference in leaf age (that is flush or mature) on DNA yield and purity were assessed. Periodically, DNA was extracted from both flush and mature leaf samples from 6 cowpea (Vigna unguiculata L. Walp.) varieties, Amantin, Asontem, Ayiyi, Bengpla, Ejura Red and Soronko beginning from the day of harvest (day 1), through day 7, 21, 35 and 49 after storage. At room temperature and simulated herbarium conditions, the yield and purity of the DNA extracted from both flush and mature leaves decreased during the period of the study. Time was found to correlate inversely with the purity and yield of DNA in all cases. Under these conditions, the yield of DNA extracted from day 1 samples (fresh samples) of both leaf types was significantly different from the DNA yield from day 7 to 49 samples. Also, no significant difference was found in DNA yield from day 7 to 49 samples. However, in most cases, more DNA was obtained from flush leaves than from their corresponding mature leaves. Of the three conditions, leaves stored at room temperature yielded the least amount of DNA. Samples kept under simulated herbarium conditions yielded more DNA than kept in the freezer but the difference was not significant. Also, a fairly constant yield and purity was obtained for DNA extracted from frozen samples. Frozen samples yielded relatively purer DNA than their corresponding samples stored either at room temperature or at simulated herbarium though the observed differences were not significant. Therefore, storage in a freezer provided the best non-chemical preservation condition among the three assessed. Only 2 (GA and AR) out of 15 random primers assayed using the technique of Random amplified polymorphic DNA-polymerase Chain Reaction, (RAPD-PCR) amplified segments of the genomic DNA extracted from the 6 varieties. Further analysis (Restriction Fragment Length Polymorphism studies) was done on the GAprimed 1200 bp PCR product using eight restriction endonucleases, Alul, Dral, £coRI, EcoRV, Haelll, Hinfl, Kpnl and Pvul. Four enzymes, Alul, Haelll. Hinfl and Kpnl digested the product. However, for each enzyme, identical banding patterns were observed on both agarose and polyacrylamide gels in all the six varieties Single stranded conformation polymorphism analysis (SSCP) was conducted on the two ARprimed products, 369 bp and 545 bp. Only the 545 bp was denatured but the profiles of the bands in all the six varieties were also identical. Therefore, these molecular techniques could not be used to identify the individual varieties