Page 43 - Teknik Menjawab Soalan PSPM Biologi

• globular protein. • decreasing the activation energy. Mechanism of enzyme action
Properties of enzyme
• increase the rate of reaction. • specific to its substrates Induced-fit model
Initial shape of active site does not exactly fit with the substrate
• do not change after the reaction. has active site which binds to its substrate.
•
• reusable after the reaction. • needed in small quantity. When substrate binds to the active sites, the shape of enzyme
active site slightly change
• denatured at extreme temperature or pH. Enable substrate to fit exactly in active site to form an
• maximum at optimum temperature or pH. Enzyme-Substrate complex
Substrate bind to active site by weak bonds (ionic bond/Hydn bond)
Shape of substrate is slightly changed
Existing bonds are broken
Enzyme classification Transition state is achieved, reaction occurs
BIOCATALYSIS Products are formed

Oxidoreductase- catalyzed oxidation-reduction reactions Shape of products differ from substrates
Transferase -catalyzed transfer of a chemical group Products no longer fit into active site
Hydrolase - Breaking a molecule by hydrolysis reactions Products are released from active site
Isomerase- rearrangement of atom within a molecule Inhibitor Active site change back to the original conformation
Lyase- Breaking a molecule without using water
Ligase- Formation of bonds between two molecules using energy
derived from the breakdown of ATP Factors that affect enzymatic reaction

reversible irreversible
Substrate concentration
pH
Temperature

Cofactor
Competitive Non-competitive

Definition
Example competitive inhibitor:
Enzyme : Succinate dehydrogenase Enzyme is a biological catalyst which increase the rate of
Substrate : Succinate biochemical reaction in living things The minimum energy needed to
Product : Fumarate break the existing bond before a
Competitive inhibitor : Malonate by lowering the activation energy (E ) reaction can occur
a
and it remains unchanged at the end of reaction