ENZIMAS - BIOQUÍMICA (ENSINO SUPERIOR) - TUDO SOBRE ENZIMAS - ESTRUTURA E FUNÇÃO DAS ENZIMAS

Summary

In this educational video, Cleverson from 'Facilitando A Medicina' delves into the essential role of enzymes in biochemistry. He explains how enzymes are crucial for accelerating chemical reactions by lowering activation energy, their dependency on factors like pH and temperature, and how some require cofactors to function. He also discusses enzyme properties, the types of inhibitors (reversible and irreversible), and the different theories explaining enzyme-substrate interactions. The video offers a clear understanding of enzyme mechanisms, their regulation, and their importance in various biochemical processes.

Takeaways

• 😀 Enzymes are essential structures in the body that facilitate reactions by lowering activation energy.
• 😀 Enzymes do not alter the overall energy of a reaction, only the activation energy required for it to occur.
• 😀 Most enzymes are proteins, but ribozymes (RNA-based enzymes) are an exception.
• 😀 Some enzymes require cofactors (inorganic ions) or coenzymes (organic molecules) to become active, forming holoenzymes.
• 😀 Enzymes need optimal conditions, including specific pH and temperature, to function effectively.
• 😀 Enzymes operate best at specific substrate concentrations, but they reach a saturation point where their activity plateaus.
• 😀 Isoenzymes are different enzymes that perform the same function but are located in different parts of the body.
• 😀 The lock-and-key theory suggests that enzymes and substrates fit together like a key in a lock, but this theory is now outdated.
• 😀 The induced-fit theory proposes that the enzyme and substrate adjust to fit each other to promote the reaction.
• 😀 Inhibitors can reduce enzyme activity, with types including competitive (competing for the active site), non-competitive (altering enzyme structure), and irreversible (permanently destroying enzyme function).
• 😀 Enzyme activity can be regulated through mechanisms such as allosteric regulation, covalent modification, and cleavage, allowing precise control over their function.

Q & A

What is the primary function of enzymes in the body?

Enzymes are structures in the body that facilitate reactions by lowering the activation energy required for the reaction to occur, making the process faster and more efficient.

How do enzymes reduce the activation energy of a reaction?

Enzymes reduce the activation energy by binding to the substrate, which alters the substrate's structure in a way that facilitates the reaction, making it occur more rapidly.

Are all enzymes proteins?

No, while most enzymes are proteins, there are exceptions. For instance, ribozymes are RNA molecules that function as enzymes.

What are cofactors and coenzymes, and how do they affect enzyme function?

Cofactors and coenzymes are molecules that assist enzymes in their activity. Cofactors are usually inorganic ions, like magnesium or iron, while coenzymes are organic substances, often vitamins. Enzymes require these components to become active.

What is the difference between apoenzymes and holoenzymes?

Apoenzymes are enzymes that are inactive without their cofactors or coenzymes, while holoenzymes are the active form of the enzyme, formed when the enzyme binds to these required molecules.

What factors influence the speed of an enzyme-catalyzed reaction?

The speed of an enzyme-catalyzed reaction can be influenced by factors such as substrate concentration, temperature, pH, and the presence of inhibitors.

What is enzyme saturation, and how does it affect enzyme activity?

Enzyme saturation occurs when all available enzyme molecules are fully occupied with substrate molecules. At this point, adding more substrate will not increase the rate of the reaction.

What are isoenzymes, and how do they function?

Isoenzymes are different forms of an enzyme that catalyze the same reaction but are found in different locations in the body or tissues.

What is the 'lock-and-key' model of enzyme function?

The 'lock-and-key' model suggests that enzymes and substrates fit together in a rigid, specific manner, much like a key fitting into a lock. However, this model is now considered outdated.

How do competitive, non-competitive, and mixed inhibitors affect enzyme function?

Competitive inhibitors bind to the enzyme's active site, preventing the substrate from binding. Non-competitive inhibitors bind elsewhere on the enzyme, altering its structure and reducing its activity. Mixed inhibitors can bind either to the enzyme or the enzyme-substrate complex, affecting the reaction rate in varying ways.