Question

biochem question

. Aspartame is an artificial sweetener that is a dipeptide composed of Asp-Phe in which the carboxyl terminus is modified by attachment of a methyl group. Draw the structure of aspartame at pH7. (4 marks) b. Calculate the isoelectric point (PI) for Aspartame. (2 marks) C. At a pH of 10 what form of ion exchange chromatography would be most appropriate to isolate Aspartame? Explain (2 marks) 2) Complete the Venn diagram with respect to the given Kd values regarding the affinity of a protein for its ligand. Place statements that apply to each individual value in each individual circle, and those statements that apply to both in the region shared by both circles. You need only write the numeral corresponding to the statement, not the entire statement in the circle: (5 marks) 2x10-5 1x 10-15 i. High affinity of protein for ligand ii. Low affinity of protein for ligand ill. Irreversible binding iv. Desirable for protein ligand interactions V. pl [PL] b. Choose one of the given Kd values listed in part a) and calculate the ligand concentration required to reach 75% saturation. (4 marks)

Answer 1

– འ བདར ར ལ བ བ ན པ ལ 0CH pK1=3, 10 OCH, pK2 = 7. 90 oCH3 པ 1. NHH ő NH₂

Aspartame is an artificial sweetener.
It is a dipeptide composed of Asp-Phe. The carboxyl group contains a methyl group.
Aspartame = Aspartyl-phenylalanine methyl ester

Structure-II (Middle structure in the image) represents Aspartame at pH = 7

pI = (7.9+3.1)/2
= 5.5

At pH = 10, Aspartame contains a net negative charge. So, if we use an anion exchange column, it will bind to aspartame. Further, we can use increasing concentrations of salt to elute it.