(1) R. Mortonemia is an extremophilic bacteria that gains its energy from a spec
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Question
(1) R. Mortonemia is an extremophilic bacteria that gains its energy from a specific protein, commonly found in yogurt, called dannonin. A researcher is studying the protein dannonin and for some reason decides that plotting the metabolic activity of R. Mortonemia will provide him insight to the properties of dannonin. R. Mortonemia is unable to consume solubilized protein. Based on the graph below, describe how to find the isoelectric point of dannonin and provide the isoelectric point.
(2) Why are left handed helices essentially unfound in nature? Focus your response on the structure of amino acids.
(3) Using the plot provided, describe why Alzheimers disease, which is characterized by Beta-amyloid aggregation, is challenging to overcome thermodynamically.
Metabolic Activity 1 2 3 4 5 6 78 9 10 11 12 13 14 pHExplanation / Answer
1) A protein has its lowest solubility when net charge on its surface is zero i.e. at isoelectric point. Since R. Mortonemia is unable to consume solubilized protein, its metabolic activity remained low when protein has some net charge on its surface.
As the protein acquires isoelectric point, it's solubity decreases (with net charge zero) and as a result of which metabolic activity shoots up as can be seen in the plot. The isoelectric point of the protein lies between 9-10.
2) Left handed helices are rarely found in nature because of the steric hindrances that result with the formation of them. The phi and psi angles in case of left handed helices results in zero gibbs free energy. Thats the reason why they are not found on Ramachandran plot.
3) With beta amyloid aggregation, the gibbs free energy of the protein decreases and it becomes non-functional. Now inorder to reverse the change or to cure Alzhiemers disease, the energy to pass the barrier so as to convert beta amyloid aggregates into fibrils is required. Thermodynamically its a difficult task to reverse beta amyloid aggregates back to functional proteins.
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