BSCI170: Cell Regulation of Enzymes

notes from 10/24

what is a transition state?

enzymes contort the substrate’s shape, making it high-energy and unstable

Types of Cell Regulation

• Competitive inhibition

• Feedback inhibition

• Noncompetitive inhibition

• Allosteric regulation

• Enzyme compartmentalization

• Cofactors

• coenzymes

What is competitive inhibition

 inhibitors bind to active site, preventing substrate from binding

What is noncompetitive inhibition

inhibitors bind to another location called the allosteric site, changing the shape of the enzyme and thus preventing substrate from binding

What is allosteric regulation

Binding of an effector (regulatory molecule) to an allosteric site

• Not always inhibitive; can either inhibit or stimulate activity

• Enzyme complex has active and inactive forms

• Binding of an inhibitor stabilizes the inactive form

• Binding of an activator stabilizes the active form

What is feedback inhibition

Effectors bind to active site

• End product of a substrate will bind to active site, thus inhibiting enzyme activity

• Prevents cell from wasting its resources and time from making too much of things it doesn’t need

What is enzyme compartmentalization

Structures within the cell (organelles) organize and make chemical reactions efficient by dictating what functions of enzymes are where

• Example, cellular respiration happens in mitochondria

Cofactors vs Coenzymes

Coenzymes: organic compounds are needed to bind substrate to enzyme

Cofactors: inorganic compounds are needed to bind substrate to enzyme

what is reaction coupling?

Reaction Coupling: cells use the energy released from exergonic reactions and reuse them in exergonic reactions

• Coupled reactions are exergonic