On the аnswer sheet prоvided tо yоu for the exаm, or scrаp paper, complete the following question: Written Response Question 4 (5 pts): Some of the most important examples of SN2 reactions in biochemistry are those catalyzed by S-adenosyl methionine (SAM) – dependent methyltransferase enzymes. In the equation to the right complete the mechanism using the curvy mechanistic arrows for the SAM-dependent methylation of epinephrine, also known as adrenaline. There are two mechanisms here, one is acid-base, the other is the methylation, that occur as one concerted process. Click to Show Image Description A biochemical reaction scheme with reactants on the left and products on the right, separated by a single-headed reaction arrow pointing to the right. On the upper left, the first reactant is S-adenosylmethionine (SAM). Its amino acid portion consists of a carbon bearing a negatively charged carboxylate (⁻O₂C) and a positively charged ammonium group (⁺NH₃), connected by a two-carbon chain to a sulfur atom carrying a positive charge (⊕). That sulfur bears a methyl group (CH₃) and is also connected to a five-membered ribose sugar ring bearing two hydroxyl groups (OH OH) at the bottom. The ribose is connected to a bicyclic purine ring system representing the adenine base, with an amino group (NH₂) at the top and multiple nitrogen atoms within the ring. On the lower left, a base (B:) is shown separately. Below it, the substrate epinephrine is drawn as a benzene ring with two hydroxyl groups on adjacent carbons. Attached to the ring is a chain consisting of a carbon bearing an OH group, connected to a CH₂ group, connected to an NH group, connected to a methyl group (CH₃), representing an N-methylamino alcohol side chain. On the upper right, the first product retains the same amino acid portion as SAM, but the sulfur atom has lost its positive charge and is now neutral (S), connected to a methylene group, with no methyl group attached. The ribose and adenine portions remain unchanged, with two hydroxyl groups (OH OH) at the bottom of the ribose and NH₂ at the top of the adenine. To the right of the arrow, B-H is shown, representing the protonated base. On the lower right, the product catecholamine is drawn with the same benzene ring and N-methylamino alcohol side chain as epinephrine, but one of the two adjacent substituents on the ring is now an OCH₃ group and the other remains an OH group.