Pyridoxal phosphate acts as a coenzyme that helps convert one of these molecules to pyruvate in a reaction with alpha-ketoglutarate. A compound consisting of three of these molecules comprises a resin used in a pulldown assay to purify molecules that are fused to an S-transferase. The SECIS element directs the production of a variant of one of these molecules that incorporates selenium. These molecules, whose D-configuration is rarely found in nature, are plotted by their phi (10[1])and psi (10[2])dihedral (10[1])angles on a Ramachandran plot. Bonds between these (10[1])molecules are cleaved by trypsin. (-5[1])These molecules, which are differentiated by their side chains, are carried by tRNAs (10[1])during translation. (10[1])For 10 points, histidine and proline are “essential” examples of what molecules that make up proteins? ■END■ (10[1])