CH19: ENZYMES & VITAMINS

OSU BIOPHRM 3311

______ is the energy associated with a chemical reaction

Gibbs Free Energy (G)

_______ is another word for reactants

Substrates

Transitional state is an ______

intermediate state

Reaction occurrence is determined by the _______-

change in G (gibbs free energy)

Activation energy is the _____

input of energy

G_R definition

Free energy of the reactants

G^‡ definition

free energy of the transition state; the peak of the energy curve

G_P definition

Free energy of the products.

Ea = G^‡ - G_R explain

Activation energy; energy required for a reaction to occur.

∆G = G_P - G_R explain

Change in free energy between reactants and products; indicates whether the reaction is spontaneous (ΔG < 0) or non-spontaneous (ΔG > 0) [have to input energy for the rxn to occur!].

Catalyst definition

substance that increases the rate of rxn by lowering the activation energy and is not consumed or changed after catalyzing a rxn

what changes in a catalyzed rxn?

rate increase and G‡ (free energy of the transition state) decrease

what is not changed in a catalyzed rxn?

G_R, G_P, and ∆G and the catalyst

enzymes definition

Are biological catalysts that within the mild conditions of temperature, pH, and pressure of the cells, carry out biochemical reactions at amazing high rates

Nearly all enzymes are _____and a few are RNA called______

• proteins

• ribozymes

enzymes are characterized by a remarkable efficiency and _______, meaning that certain enzyme recognizes ________.

• specificity (substrate and stereoisomerism)

• only certain substances

Some enzymes require non-protein part, called _______ (such as mineral and vitamin) to function.

co-factors

conjugated proteins definition

proteins that incorporate one or more non–amino acid units (co-factor) in its structure (compare to simple proteins)

turnover number definition

the number of substrate molecules converted into product by an enzyme molecule in a unit time - how catalytic activity of an enzyme is measured