BAHAN KULIAH BIOKIMIA POWER POINT BAGIAN 1 /BIOCHEMISTRY POWER POINT LECTURES PART 1 | Karya Tulis Ilmiah

Enzyme Catalysis
3/17/2003

General Properties of Enzymes
•Increased reaction rates sometimes 106 to 1012 increase
Enzymes do not change G just the reaction rates.
•Milder reaction conditions
•Great reaction specificity
•Can be regulated

Substrate specificity
The non-covalent bonds and forces are maximized to
bind substrates with considerable specificity
•Van der Waals forces
•electrostatic bonds (ionic interactions)
•Hydrogen bonding
•Hydrophobic interaction

A+B
Substrates

enz

P+Q
Products

Enzymes are Stereospecific
O


CH 3CH 2 OH  NAD  CH 3CH  NADH  H
Yeast
Alcohol dehydrogenase



H

O

C

CH3CD2OH +

+

N

NH2

NAD+

Ox.
D

H

O
CH3C-D

O

C

+
N

Pro-R hydrogen gets pulled off

NADD

Yeast Alcohol dehydrogenase

NH2

Red.

OH

O
2. NADD + CH3-C-H

H

C

D

CH3

O

OH

3. CH3-C-D + NADH
D

C

H

CH3

If the other enantiomer is used, the D is not transferred
YADH is stereospecific for Pro-R abstraction

Both the Re and Si faced transfers yield identical
products. However, most reactions that have an Keq
for reduction >10-12 use the pro-R hydrogen while those
reactions with a Keq