StickaseSubstrateIf enzyme just binds substrate then there will be no further reactionTransition stateProductEnzyme not only recognizes substrate, but also induces the formation of transition stateAdapted from Nelson & Cox (2000) Lehninger Principles of Biochemistry (3e) p.252X

The Nature of Enzyme Catalysis Enzyme provides a catalytic surface This surface stabilizes transition state Transformed transition state to productBCatalytic surfaceAJuang RH (2004) BCbasics

Enzyme Stabilizes Transition State SPESESTEPSTEnergy changeEnergy required (no catalysis)Energy decreases (under catalysis)Whats the difference?T = Transition stateAdapted from Alberts et al (2002) Molecular Biology of the Cell (4e) p.166

Active Site Is a Deep Buried PocketWhy energy required to reach transition stateis lower in the active site?It is a magic pocket(1) Stabilizes transition(2) Expels water(3) Reactive groups(4) Coenzyme helps(2)(3)(4)(1)CoE+-Juang RH (2004) BCbasics

Enzyme Active Site Is Deeper than Ab BindingInstead, active site on enzymealso recognizes substrate, butactually complementally fits the transition state and stabilized it.Ag binding site on Ab binds to Agcomplementally, no further reactionoccurs. Adapted from Nelson & Cox (2000) Lehninger Principles of Biochemistry (3e) p.252X

Active Site Avoids the Influence of WaterPreventing the influence of water sustains the formation of stable ionic bondsAdapted from Alberts et al (2002) Molecular Biology of the Cell (4e) p.115-+

Lehninger Stickase Stickase () (abzyme)

(1) (2) (3) ( Ser-OH) ( His H+) ( Ser-O-)(4)

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