ENZIMAS - BIOQUÍMICA | Biologia com Samuel Cunha

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The instructor introduces the topic of enzymes, highlighting their relationship to proteins and emphasizing exceptions in biological compounds.

Enzymes: Proteins and Exceptions

• Enzymes are proteins, but not all proteins are enzymes. There are exceptions in biology where variations exist.

• Ribozymes, a type of enzyme formed by RNA, play a role in protein synthesis within cells. They are exceptions to the typical protein-based enzymes.

• Enzymes exhibit advanced information processing capabilities. While most enzymes are proteins, a small subset like ribozymes deviate from this norm.

Exploring Enzyme Specificity

The discussion delves into the specificity of enzymes using the analogy of "lock and key," emphasizing how enzymes interact with substrates.

Lock-and-Key Specificity

• Enzymes demonstrate specificity akin to a lock-and-key mechanism where each enzyme interacts uniquely with its substrate.

• The concept of induced fit suggests that when a substrate binds to an enzyme, slight modifications occur in the enzyme's structure for optimal interaction.

Historical Context and Discoveries

A historical perspective on enzyme discovery is provided, attributing significant findings to past researchers.

Discovery and Significance

• Enzymes were first recognized by scientists studying fermentation processes in the 19th century, leading to the term "enzymes" coined by William Kühne in 1878.

Understanding Enzymes and Their Functions

In this section, the speaker discusses the importance of enzymes in the body's processes, focusing on how they aid in digestion and various industrial applications.

Enzyme Function and Importance

• Enzymes are essential for digestion as they help break down molecules like proteins into amino acids.

• Enzymes are present not only within cells but also in bodily fluids like pancreatic juice, aiding in digestion.

• Enzymes act as catalysts, lowering the energy required for reactions to occur, thus increasing reaction speed.

• The enzyme 5-phosphatase decarboxylase exemplifies how enzymes significantly accelerate reactions compared to without them.

Industrial Applications of Enzymes

• Enzymes find extensive use in industries such as cheese production and odor control in food processing.

• Specific enzymes play crucial roles in processes like fermentation to remove bitterness from products like cocoa.

Diverse Enzyme Functions

• Various enzymes like catalase, lactase, proteases are vital for breaking down substances such as lactose and proteins efficiently.

Understanding Enzymes and Their Functions

In this section, the instructor explains the specificity of enzymes to substrates, the concept of induced fit, and how enzymes act as catalysts in biochemical reactions.

Enzyme Specificity and Induced Fit

• Enzymes are highly specific to their substrates, fitting like a "lock and key" where the enzyme's shape perfectly matches the substrate.

• The induced fit theory describes how enzymes undergo a slight modification in shape upon binding to substrates, enhancing catalytic activity.

Enzyme Catalysis and Reaction Speed

• Enzymes act as catalysts by lowering the activation energy required for a reaction, significantly increasing reaction speed.

• The active site of an enzyme where substrate binding occurs is known as the catalytic center, facilitating enzyme-substrate complex formation.

Importance of Enzymes in Biological Processes

This part emphasizes the vital role of enzymes in accelerating reactions and enabling life processes.

Enzymatic Functionality

• Enzymes facilitate reactions by decreasing activation energy and speeding up chemical transformations.

• Through enzymatic action, substrates are converted into products while keeping the enzyme available for subsequent reactions.

Factors Influencing Enzyme Activity

The discussion focuses on factors affecting enzyme function such as temperature sensitivity.

Temperature Influence on Enzyme Activity

• Temperature plays a crucial role in enzyme activity; extreme temperatures can denature proteins, leading to loss of function.

Temperature Regulation and Enzyme Activity

The discussion revolves around the relationship between body temperature, fever, and enzyme activity. It explains how the body's defense mechanism involves raising temperature to combat infections effectively.

Body Temperature and Fever

• When infected, the body may experience hyperthermia, commonly known as a fever, with temperatures above 38.85 degrees Celsius.

• Elevated body temperature serves as a defense mechanism against infections by weakening bacterial enzymes at higher temperatures.

• Excessive temperature increase beyond 39 degrees Celsius can lead to enzyme denaturation, causing severe issues or even death.

Enzyme Activity and pH Levels

This segment delves into how enzyme activity is influenced by pH levels in different parts of the digestive system, showcasing examples of pepsin and trypsin.

Enzymes in Digestive System

• Pepsin functions optimally in highly acidic environments like the stomach (pH ~2), while trypsin operates best in slightly basic conditions found in the small intestine (pH ~7).

• Pepsin and trypsin exemplify how enzyme activity varies based on pH levels, crucial for efficient digestion processes.

Enzymatic Reactions and Substrate Concentration

This part elucidates how enzyme-substrate concentration impacts enzymatic reactions' efficiency through saturation points.

Enzyme Saturation

• Enzyme activity increases with substrate concentration until reaching saturation where further substrate addition doesn't enhance reaction rates due to limited enzyme availability.

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In this section, the speaker discusses enzyme inhibitors and their impact on enzyme function.

Enzyme Inhibitors

• Enzyme inhibitors can affect enzyme activity by binding to the active site or another part of the enzyme.

• There are reversible inhibitors that can bind to the enzyme temporarily and then dissociate, allowing the enzyme to function again.

• Competitive inhibitors compete with the substrate for binding to the active site, hindering substrate binding and enzyme activity.

• Non-competitive inhibitors bind to a different site on the enzyme, altering its shape and preventing substrate binding effectively.

• Irreversible inhibitors like cyanide form strong bonds with enzymes, permanently inactivating them and leading to severe consequences such as cell death.

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This section delves into irreversible enzyme inhibitors like cyanide and their dangerous effects on cellular processes.

Irreversible Enzyme Inhibitors

• Irreversible inhibitors like cyanide form strong bonds with enzymes, leading to permanent inactivation.

• Cyanide's action on enzymes involved in cellular respiration can be lethal due to its irreversible nature.

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The speaker concludes by emphasizing key points about protein structure and resources available for further learning.

Protein Structure and Resources

• Understanding protein structure, including amino acids and peptide bonds, is crucial for comprehending enzymatic reactions.