An Overview of Metabolism and Biochemical Energy An energetically unfavorable reaction "couples"with an energetically favorable reaction so that the overall free- energy change for the two reactions together is favorable Coupled reactions Imagine that reaction 1 does not occur to any reasonable extent because it has a small equilibrium constant and is energetically unfavorable,the reaction has AG 0 (1)A+m二B+n△G>0 where A and B are the biochemically "interesting"substances undergoing transformation,while m and n are enzyme cofactors, H2O,or other substances An energetically unfavorable reaction “couples” with an energetically favorable reaction so that the overall free￾energy change for the two reactions together is favorable Coupled reactions ▪ Imagine that reaction 1 does not occur to any reasonable extent because it has a small equilibrium constant and is energetically unfavorable, the reaction has ∆G > 0 (1) A + m B + n ∆G > 0 where A and B are the biochemically “interesting” substances undergoing transformation, while m and n are enzyme cofactors, H2O, or other substances An Overview of Metabolism and Biochemical Energy