Enzyme Structure and Function

Enzyme Structure and Function

• Enzymes are biological catalysts that speed up biological processes.
• Ribozymes are biological catalysts that consist of RNA.
• The active site of an enzyme interacts with the substrate (reactant).
• The active site's shape is specific to the enzyme and its function.
• Substrate and active site shapes must match for the enzyme to function effectively.
• Compatible charges on amino acid R-groups in the active site and substrate are necessary.

Environmental Factors Affecting Enzymes

• Enzymes catalyze reactions at optimal temperatures and pH levels.
• Low temperature results in infrequent enzyme-substrate collisions, slowing down the reaction.
• High temperature causes enzyme denaturation, altering substrate-enzyme bonds and enzyme shape.
• Different pH levels can disrupt enzyme bonds and alter the enzyme's tertiary structure.
• Denaturation is a change in enzyme structure, limiting its catalytic ability.
• Denaturation can sometimes be reversed if conditions return to optimal levels.

Enzyme Inhibition

• Competitive inhibitors compete with substrates for the active site of the enzyme.
• Competition lowers enzyme-substrate reaction rates.
• Substrate concentration increase reduces the effects of competitive inhibitors.
• Non-competitive (allosteric) inhibitors bind to a different site on the enzyme, altering its shape and active site structure.
• Non-competitive inhibition is unaffected by substrate concentration.
• This type of inhibition plays a crucial role in feedback mechanisms to regulate cell processes.

Cofactors and Coenzymes

• Cofactors (inorganic molecules) and coenzymes (organic molecules) enhance enzyme efficiency.
• They typically bind to the active site or substrate to improve substrate binding.

Activation Energy

• All molecules possess free energy (G).
• Chemical reactions in biological processes involve changes in molecular energy (endergonic or exergonic).
• Endergonic reactions have products with higher energy than reactants.
• Exergonic reactions have products with lower energy than reactants.
• All reactions require activation energy (Ea) to reach the transition state.
• Higher activation energy leads to slower reactions.
• Lower activation energy leads to faster reactions.
• Enzymes lower activation energy by: orienting substrates for reaction, destabilizing substrate bonds, and forming temporary bonds with substrates.
• Enzymes do not alter whether a reaction is endergonic or exergonic.

Energy and Metabolism/Coupled Reactions

• Cell energy input must exceed requirements.
• Energy-releasing processes can be coupled with energy-requiring processes to enhance efficiency.
• Coupled reactions occur in multi-step processes for controlled energy transfer.
• Coupling an exergonic reaction (e.g., ATP breakdown) with an endergonic reaction (e.g., sucrose synthesis) allows for energy transfer.

Test your knowledge on enzyme structure and function with this quiz. Explore the role of enzymes as biological catalysts and how environmental factors such as temperature and pH affect enzyme activity. Dive deep into concepts like active sites and the importance of substrate compatibility.