Question

can you solve the following chemistry/Biochemistry questions. thank you in Advance!

Activity: Skill Development 1. Do you think a denatured protein is biologically active? Support your answer. 2. When lemon juice is added to milk, the milk curdles. Why does lemon juice have this effect? What is happening to the proteins in the milk? 3. Some denaturation of proteins can be reversible. Which of the following denaturations do you think can be reversible? a. Heating a protein above 50 °C b. Changing the pH by 1 pH unit. Adding mercury to a protein. с.

Answer 1

1.No,denatured protein is not biologically active.Because when a protein denatured its secondary and tertiary structures are disrupted but the peptide bonds of the primary structure between the amino acid is not altered. Since all structural levels of the protein are responsible for its function, the protein can no longer perform its function once it has been denatured.

2.Curdled milk is a common example of denatured protein.Milk contains a specific type of protein namely casein in the form of small particles and it has a tendency to aggregate and get precipitated.The grouping of casein particles is prevented because they have a negative charge, which makes them repel other groupings of casein and keeps the casein evenly dispersed in the milk.But when lemon juice is added, it increases milk's acidity as lemon contains citric acid.The negative charge on the casein groupings becomes neutralized. So instead of pushing each other apart, the casein starts to clump together. Eventually large enough clumps are formed and milk curdles.

3.I think changing the pH of protein by 1 unit reverse the denaturation of protein.When the pH of a solution containing protein is changed, the protonation state of the amino and carboxylate groups changes, and ionic bonds and salt-bridges in proteins is disrupted .If the pH change is small, reversal of the pH change will often regenerate the native structure.