Uncatalyzed reaction △G+A→B) △G(B→A) △GA→B Catalyzed △G(B→A reacton Reaction coordinate
12-13 ENZYMES ARE COMPLEMENTARY TO TRANSITION STATE, NOT SUBSTRATE (a)No enzyme AG Substrate Transition state Products (metal stick <bent. stick (broken stick) (b) Enzyme complementary to substrate Magnets S FITS ETOO WELL: WOULD HAVETO BREAK INTERACTIONS 358 anat|△G IN ORDERTO REACH G TRANSTICN STATE ESmore stable less free energy than salone (e)Enzyme complementary to tran siLion state AG INCREASE /N FREE ENERGY REQUIRED TO BEND S Reaction coordinate INTOTRANSTICN STATE OFFSET BY INCREASED INTERACTIONS BETWEEN E AND SIN TRANST/C STATE- BINDING ENERG
12-13A ENZYMES ARE COMPLEMENTARY TO TRANSITION STATE (e)Enzyme complementary to transition state 边 Reaction coordinate When S first binds, only a subset of binding interactions is used to fornES Bound s must still undergo an increase infree energy to reach transition state But now, the increase iniree energy required to bend stick intotransition state is offset ( paid for )by the increased interactions, sit (ie. binding energy) that form betweenE and S in the transition state Many interactions involve parts ofs that are distant from the point of reaction, so interactions betweenE and the non-reacting part ofs provide some of the energy need to catalyze " stick"breakage The binding energy contributed by the formation of weak interactions between E and s in the transition state provides much of the energy needed to lower activation energy Binding energy provides major driving force for catalysis
Energy diagram H-O transition H-O o-H state reactants activation energy 2H2O2 products △H 2 Hoo+O. 2
Enzymatic reactions enzymatic activation energy 2 H2O 2 △H 2 Ho+o