81

(Phototroph Phototrophic organism)

() (Chemotroph Chemotrophic organism)

(Energy)

- (Chemical reaction)

82

Respiration

ATPADP + Pi

Food + O2 CO2+ H2O

Chemicalwork

Mechanicalwork

Electricalwork

Transportwork

ATP

-

-

(Catalyst)

(Biocatalyst Organic catalyst) (Enzyme)

83

(Specificity) (Substrate)

1. (Lock and key theory) (Emil Fischer)

(Active site) (Substrate) ( )

Enzyme Substrate Enzyme-Substratecomplex

Product

(E) (S)

SubstrateActive site

Enzyme Enzyme-Substrate complexEnzyme

a. Degradative reaction

Enzyme Enzyme-Substrate complex Enzyme

Products ProductSubstrates

Active site

b. Synthetic reaction

a. b.

2. (Induced-fit theory) (Koshland) ( (Active site) )

84

Enzyme(Note active site

larger than substrate)(b) Induced fit model

Enzyme-Substratecomplex (Enzymechanges shape)

complexEnzyme-Substrate

(a) Lock-and-key model

SubstratesEnzyme

Substrates

(a) ()(b) (

)

(Inhibitor) (Inhibitor)

1. (Competitive inhibitor) (Substrate)

(Active site) (Succinic acid) (Malonic acid) (Oxalic acid) (Cyanide)

2. (Noncompetitive inhibitor) (Active site)

Substrate

(a) (b)

Competitiveinhibitor

EnzymeEnzyme

(c)

Noncompetitive

Enzyme

Substrateinhibitor

(a) - (ES complex)(b) - (EI complex)(c) - (ESI complex EI complex)

85

Energy ofactivation Energy of

reactant Energy ofactivationEnergy ofreactant

Energy ofproduct

Energy ofproduct

Energ

y Rele

ased

Energ

y Sup

plied

Energ

y Rele

ased

Energ

y Sup

plied

E without Enzymea E with Enzymea

()

(Bond energy)

2 1. (Exergonic reaction) >

()

>

ATP + H2O ADP + Pi + 7.3 kcal/molC6H12O6 + 6O2 6CO2 + 6H2O + 36 ATP

2H2 + O2 2H2O + 2. (Endergonic reaction)