Answer to Question #52449 in Biochemistry for Ashley

Question

If you had a solution of proteins from a crude extract in water, and added ammonium sulfate to 60% saturation, proteins with more hydrophobic surfaces exposed precipitate. If you then heated the solution to 60 degrees Celsius for 2 minutes, and then put the solution on ice, less-thermostable proteins will denature, and more more hydrophobic areas will be exposed on these proteins. Meanwhile, more-themostable proteins will not be denatured and remain in their native state. If you were designing a purification procedure to separate proteins on thermostability, after centrifuging, would you expect the less-theromostable proteins that are denatured to become less soluble and precipitate? Would this 60 degree Celsius heat treatment step cause more proteins to precipitate and become part of the pellet than before the step? How would you draw a flow chart for this step of a purification procedure?

Answer 1

Most proteins denature when heated in solution at 60°C. They become less soluble and, therefore, precipitate. I would suggest to use a diagramme how the precipitated pellet is formed upon 60 degree Celsius heat treatment.