Q28 Epinephrine has the following structure. Which of the following amino acids are used by theepinephrine receptor to interact with epinephrine via hydrogen bonds and electrostaticinteractions?HOHOPhe and GlnO Ser and AspLys and TyrO Val and ThrGlu and LeuOHHNH+

Epinephrine is an amphoteric drug which contains basic amine (pKa 8.7) and two acidic phenols groups (pKa 10.2 and 12.0). Amphoteric molecules can work as both base and acid. Alpha carbon of amino acids contains a carboxyl group, an amine group and a side chain group. Based on the side chain amino acids can charged polar, uncharged polar and non-polar. Phe, Val, and Leu are hydrophobic/non-polar amino acids that do not participate in H bonds or ionic interactions. Glu and Asp are negatively charged acidic amino acids which is repelled by the partial negative charge on oxygen. It can form ionic interaction with positively charged group in Glu and Asp deprotonated state. Lys is positively charged basic amino acids which is repelled by the partial positive charge on nitrogen. It can form ionic interaction with negatively charged group in Lys protonated state. Tyr is hydrophobic aromatic acids but its side chain group work as a uncharged polar amino acids with pKa value of 10.07 and it can form hydrogen bond. Gln is a uncharged polar amino acid. Epinephrine can interact with acidic polar amino acids (Glu and Asp) by ionic interaction and uncharged polar amino acids (like Ser, Thr, and Tyr) by hydrogen bonds. a. Phe and Gln: Phe is non-polar amino acids and cannot interact with epinephrine. Gln is uncharged polar amino acids and also cannot interact with epinephrine. incorrect option. b. Ser and Asp: Epinephrine can interacts by hydrogen bond (its -OH group forms hydrogen bond with -OH group of Ser) and ionic interaction (protonated nitrogen atom of it will interacts with negatively charged Asp side chain group). correct option. c. Tyr and Lys: Tyr will form H bond with epinephrine while the Lys cannot interact via ionic interactions as both Lys and epinephrine contains basic amine group (positively charged, repulsion happens). incorrect option. d. Val and Thr: Thr can interact with epinephrine by hydrogen bond. While, Val is non-polar amino acids and cannot interact with epinephrine. incorrect option. e. Glu and Leu: Glu is acidic amino acid which can interact with amine group of epinephrine by ionic interaction but Leu is non-polar amino acid and cannot interact with epinephrine. incorrect option. So, the correct answer will be option (b) Ser and Asp.