ABI 102 Lecture 16: Enzyme Regulation

Long-acting insulin was engineered to have a pl that resulted in an insulin protein that was completely soluble at pH 4, but forms insoluble hexamers at a physiological pH of 7.4. What is the pl of a protein?

Q) If a person's blood pH is too low, mechanisms are in place toraise the pH and reestablish homeostasis. if the pH is too low,would a person's respiratory rate increase or decrease to correctit, and how would it make a difference?

In what order will the proteins in the above problem elute from a DEAE-cellulose (diethylaminoethyl- cellulose) anion exchange column at pH 8.5? Protein A, Mr 48,000, pI 7.8; protein B, Mr 16,000, pI 6.4; protein C Mr 41,000, pI 5.6

a. A, B, C

Can someone explain why the order is from A ---> C ? It seems to me like it would be the other way around; from greatest difference between pH and pI to least difference between pH and pI. Thanks!