C1.1 Enzymes and Metabolism

Catalyst

A substance that speeds up rate of reaction

Metabolism

Chemical reactions in the body that convert food into energy

Catabolic Reaction

Breaks one substrate into smaller products

Anabolic

Forms one product from smaller substrates

Active site of enzymes

The shape is complementary and highly specific to its substrates, so that it can bind to it

Induced-fit binding

The enzyme and substrate undergo conformational change to complement each other

Collision Theory

Chemical reactions occur when the reactants randomly collide

Enzyme-substrate specificity

The shape and chemical properties of an enzyme’s active site allow only specific substrates to bind

Denaturation

When a protein loses its 3D conformation and is unable to function as usual

The effect of temperature on enzymes

High temperatures increases enzyme activity, but extreme temperatures can denature enzymes

Which structure does temperature effect

Secondary structure - disruption of hydrogen bonds

Effect of pH on enzymes

Enzymes are more active in their optimum pH, but can denature at extreme levels

Which structure does pH effect

Tertiary structure - affects ionic bonds

Activation Energy

Invested energy for reaction to occur

How do enzymes affect activation energy

Enzymes lower activation energy of a reaction

Where are intracellular enzymes produced?

In the cytoplasm, by free ribosomes

Where are extracellular enzymes produced?

Synthesized by ribosomes attached to the ER, then released from the cell

Allosteric site

“second active site” from the enzyme changing shape

Non-competitive Inhibition

Inhibitors bind to allosteric site prevents catalysis

Competitive Inhibition

Inhibitors bind to the active site of enzymes to prevent substrates from binding

Feedback inhibition

Occurs when there is an excess of the end-product of a reaction pathway, where the product inhibits its produciton

Example of feedback Inhibition

Isoleucine inhibits Threonine to reduce its own production

Mechanism-based/irreversible Inhibition

Inhibitor permanently binds to active site of enzyme

Example of mechanism-based inhibition

Penicillin inhibits transpeptidase