Biochemistry 4th Edition by Christopher Mathews,Kensal van Holde, Dean Appling, Spencer Anthony Cahill

Exercise 3

Note that some of these problems refer to information presented in the Tools of Biochemistry 5A-D.
(a) Sketch the titration curve you would expect for a-melanotropin (Problem 2). Assume the p K a s of the N- and C-termini are, respectively, 7.9 and 3.8. For side chains, assume the pK a values given in Table 5.1.
(b) Calculate to 3 decimal places the charge on a-melanotropin at pH values of 11, 5, and 1.
(c) Calculate the isoelectric point of a-melanotropin.
For parts (b) and (c) of this problem refer to the logic used to solve Problem 2.16. You may find a spreadsheet useful to solve part (c).