Folate is a chemical used by cancer cells to make DNA during cell division. Folate is produced through the conversion of folic acid catalysed by the enzyme dihydrofolate reductase.
Methotrexate is a medicinal drug given to people with cancer, and other autoimmune diseases, as it acts as an inhibitor for the enzyme dihydrofolate reductase.
The image below shows the chemical structure for the enzyme's normal substrate, folic acid, as well as the structure of its inhibitor, methotrexate.
Using the images, suggest the method of inhibition used by methotrexate. Explain your answer.
There are many enzymes that are unique to cancer cells. Designing drugs to specifically target those enzymes could remove many difficult side-effects for the patients.
Reference to databases of information detailing the action and chemical structure of different chemicals could aid scientists in identifying a suitable chemical to tackle cancer cells without the same impact on other body cells seen in the use of methotrexate.
State the name given to this method of chemical identification and suggest how it might it be used to identify suitable cancer drugs.
The investigation was extended to compare the initial reaction rates of trypsin obtained from different species of animal.
Suggest two advantages of calculating the initial reaction rates of enzyme catalysed reactions here rather than the reaction rates at another point during the experiment.
Plasmodium falciparumis a protozoan parasite of humans that causes malaria. Scientists have sequenced the proteome of this parasite and have determined a number of enzymes involved in its metabolic pathways. One such enzyme is hexokinase which is involved in the phosphorylation of glucose within the parasite.
The scientists tested two potential enzyme inhibitors, Inhibitor A and Inhibitor B, on the activity of hexokinase. The results are shown in the graphs below.
Compare and contrast the effect of the two inhibitors on the percentage inhibition.
The Plasmodium falciparum parasite depends on glycolysis for its survival, particularly the uptake of glucose from its host cells which is mediated by hexokinase.
The scientists investigated the action of hexokinase within Plasmodium falciparum. They tagged hexokinase with two different potential drugs that inhibit its action. Their results are shown in the graph below.
Describe how to calculate the rate of reaction from the graph.
