Question 4Use the following key to answer the next questions:A. Using one letter code, write out the reaction scheme for the stepwise de-protonationof this amino acid from the fully protonated to the fully de-protonated form. Clearlyindicate the net charge of each form.B. Which of the above forms do not exist at any pH?C. Which form(s) would predominate after you added one mole of NaOH to one mole ofform ‘E’?D. Estimate the pH after you mixed equal molar amounts of A and D.

Which amino acid is ideal for the transfer of protons within the catalytic site of enzymes due to the presence of significant amounts of both the protonated and deprotonated forms of its side chain at biological pH?Answers: A. AlanineB. AsparagineC. TyrosineD. CysteineE. Histidine

Draw an α amino acid with an ethyl −−CH2CH3 side chain. Draw the molecule as it would appear at physiological pH.

A new amino acid with a basic side chain has been identified with the following pka values:pKa (-COOH)  =  2.10pKa (-NH3+)    =  9.44pKa (basic side chain) = 10.51What is the charge at pH = 1.50? (you don't have to include the "+" for positive charges but you do need to include the "-" for negative charges)

Suppose you have solutions of the following amino acids buffered at a pH of 7.0. In which of the solutions would the major species have no net charge?. SELECT ALL THAT APPLYA. Histidine (6.0)B. Glutamic Acid (4.2)C. Cysteine (8.3)D. Isoleucine (>14)E. Lysine (10.0)

What is the net charge on the amino acid lysine at pH = 7.4 if pKa1 = 2.16, pKa2 = 9.06, and the pKa of the side chain = 10.54?A.+1B.+2C.0D.-1