4.2 The rate constant of a reaction(k) is related to the free energy difference between the transition state and the ground state of the substrate(Agt) 4.2.1 Transition state is a fleeting molecular moment (not a chemical species with any significant stability) that has the highest free energy during a reaction。 4.2.2 An enzyme increases the rate constant of a reaction(k by lowering its AGt. 4.2.3 The combination of a substrate and an enzyme creates a new reaction pathway whose transition state energy is lower than that of the reaction in the absence of energy
4.2 The rate constant of a reaction (k) is related to the free energy difference between the transition state and the ground state of the substrate (G‡ ) 4.2.1 Transition state is a fleeting molecular moment (not a chemical species with any significant stability) that has the highest free energy during a reaction. 4.2.2 An enzyme increases the rate constant of a reaction (k) by lowering its G‡ . 4.2.3 The combination of a substrate and an enzyme creates a new reaction pathway whose transition state energy is lower than that of the reaction in the absence of energy
Transition state() O5 △G S→>P △GP→>s S △G F Ground state Ground state Reaction coordinate
Transition state() △G uncat △G ESTEP cat S P Reaction coordinate
table 8-4 Relationship between Kea and△G° (see Eqn 8-3) K △G°( k/mol) 10-6 34.2 10-5 28.5 10-4 22.8 10-3 17.1 10-2 11.4 10 5.7 0.0 101 5.7 10 11.4 10 17.1
5. Formation of an enzvme-substrate complex is the first step in enzyme le catalysis 5.1 Substrates are bound to a specific region of an enzyme called the active site 5.1.1 Much of the catalytic power of enzymes comes from their bringing substrates together in favorable orientations in enzyme-substrate (ES) complexes (mutations that affect the on-rate the off rate,kcat,…,etc) 5.1.2 Most enzymes are highly selective in their binding of substrates. 5.1.3 The active site usually takes up a relatively small part of the total volume of an enzyme. 5.1. 4 The active site is a three-dimensional entity formed by groups that come from different parts of the linear amino acid sequence
5. Formation of an enzyme-substrate complex is the first step in enzyme catalysis. 5.1 Substrates are bound to a specific region of an enzyme called the active site. 5.1.1 Much of the catalytic power of enzymes comes from their bringing substrates together in favorable orientations in enzyme-substrate (ES) complexes. (mutations that affect the on-rate, the offrate, kcat, …etc). 5.1.2 Most enzymes are highly selective in their binding of substrates. 5.1.3 The active site usually takes up a relatively small part of the total volume of an enzyme. 5.1.4 The active site is a three-dimensional entity formed by groups that come from different parts of the linear amino acid sequence