A Comparison Study For Cytosine Deaminase Production From Saccharomyces Cerevisiae Of Different Ready-Made Bread Yeast Types Purchased From Local Market

Background: In the current study the enzyme cytosine deaminase was extracted from the ready-made bread Saccharomyces cerevisiae yeast represented different types from the local market. Methodology: About 100 grams were subjected to 50 ml toluene with the aid of gentle heating at 45°C. Then100 ml cold water was added and incubated at 4°C for 18 hours, then the water layer was centrifuged and subjected to different purification steps for the enzyme including precipitation with salt, ion exchange, and gel filtration purification process. Results: The local Iraqi type gave an average specific activity of 12.267 U/mg as the best result, the specific activity for enzyme after DEAE-cellulose purification was 216.66 U/mg. The specific activity reached 571,428 IU/mg after the Sephadex G-200 gel exclusion step. Conclusion: The choice of bread yeast for extracting the cytosine deaminase enzyme is due to its ready availability, fast growth and reproduction, dense growth, and lack of any negative impact on human health. Among the tested yeast strains, the local yeast strain Iq.3 demonstrated superior efficiency in enzyme production when compared to others. Given the characteristics of the local yeast, it is crucial to investigate and utilize its potential for medical applications.