ENZYMES!

What are Enzymes?• PROTEINS!

• Act as a catalyst to speed up chemical reactions

• They are NOT permanently changed in the process

• Reusable!

• Specific!

• End in –ase– Sucrase– Maltase– Lactase

How Do Enzymes Work?

• Enzymes weaken bonds between compounds– This reduces the amount of energy needed to

start a reaction

En

erg

y

Progress of the reaction

Reactants

Products

Without EnzymeWith Enzyme

Enzyme-Substrate Complex• The substance the enzyme reacts on is the

substrate

• The area where the enzyme binds to the substrate is the Active Site

EnzymeSubstrate

Active Site

What Can Affect Enzyme Activity?

• Environmental Conditions

• Cofactors and Coenzymes

• Enzyme Inhibitors

• Temperature– High temperatures can unfold enzymes– Most reactions require a specific temperature

range to occur reliably

• pH

– Most reactions require a neutral pH to occur

Environmental Conditions

• Inorganic substances and vitamins are sometimes needed for enzymes to function properly

• Ex: Iron must be present in the structure of hemoglobin in order for it to pick up oxygen

Cofactors and Coenzymes

Enzyme Inhibitors• Inhibit the function of a specific enzyme• Competitive or noncompetitive

• Competitive Inhibitors– Resemble the enzyme’s normal substrate and

compete with it for the active site

Enzyme

Competitive inhibitor

Substrate

Enzyme Inhibitors

• Noncompetitive Inhibitors – Do NOT enter the active site!– Bind to a different area of the enzyme

• This causes the enzyme to change its shape, which alters the active site

• The enzyme can no longer bind to the substrate

EnzymeAlteredActive site

NoncompetitiveInhibitor

Substrate