Using abbreviations (not structures), write the reaction of flavin adenine dinucleotide that gives off energy (-AG). Match the items in the left column to the appropriate blanks in the equation on the right. H+ FADH → FADH3 + |H* 3/2H2 FADH3 FAD FADH 2H+ FADH2 3H+ H2

In addition to the reactions mentioned in Section 23.5, PLP can catalyze b-substitution reactions. Propose a mechanism for the following PLP-catalyzedb-substitution reaction:

Many enzymes are switched "on" by attachment of a phosphate group at a specific serine somewhere on the protein (phosphorylation). The basic reaction is: E + ATP2 Ep + ADP Po SERINE PHOSPHO SERINC (Note the "squiggles" before the backone amide and carbonyl indicate the polypeptide chain continues on either side of the serine). For phosphorylation to have this effect, there has to be some equilibrium between inactive and active forms conformations of the enzyme: [Eactive] [Einactive] Einactive 2 Eactive; K* The same basic equilibrium must exist for the phosphorylated protein: [Ep,active] [Ep,inactive] EP,inactive 2 Ep,active; Kp = (a) If phosphorylation increases the measured activity of the enzyme, is K* or K larger? Why? (b) Does the phosphorylation site need to be near the site where the enzyme binds its substrate (e.g. the reactant whose chemistry it catalyzes)? Why or why not?

The following are structural diagrams of a selection of newly discovered amino acids. OH -の-CHs NH HO C-OH NH, AN-CH CH2 CH2 OH Ho NH, C=0 a) Select 1 amino acid. Redraw it. Label the alpha carbon and circle/highlight the entire backbone of the amino acid. b) The amino acids are part of a channel protein embedded in the cell membrane. Choose 2 amino acids (from above) that you would expect to find within the interior/middle of the cell membrane. Draw the formation of the dipeptide using the 2 amino acids you selected. Identify the other products formed in the reaction.