About this video

• Video Title: Metabolism - Enzymes II (Part 1) | BIALIGY.com
• Channel: BIALIGY
• Speakers: Not specified
• Duration: 00:09:42

Overview

This video explains the structure and function of enzymes, focusing on how they work at a molecular level. It details the role of the active site, the interaction with substrates, and introduces the induced fit model, contrasting it with the older lock and key model.

Key takeaways

• Enzymes are Proteins: Enzymes are typically globular proteins with tertiary or quaternary structures, which define their function.
• Active Site: Enzymes possess specific indentations or grooves called active sites. These are the regions where enzymes interact with substrates.
• Substrate Specificity: Each enzyme is specific to a particular substrate, meaning it can only act upon one or a limited range of substances. This is exemplified by sucrase acting only on sucrose.
• Enzyme-Substrate Complex: When an enzyme binds to its substrate, it forms an enzyme-substrate complex.
• Induced Fit Model: This model describes how the enzyme's active site changes shape upon binding with the substrate, creating a tighter fit. This conformational change facilitates the enzyme's catalytic activity, often involving the breaking of bonds.
• Shift from Lock and Key: The video notes that the induced fit model has largely replaced the older "lock and key" analogy for enzyme-substrate interaction, as it better explains the dynamic nature of this process.

The "lock and key" model proposed that an enzyme's active site had a rigid shape that perfectly matched the substrate, much like a key fits into a lock. In contrast, the induced fit model suggests that the enzyme's active site is more flexible. Upon binding with the substrate, the active site undergoes a conformational change, adapting its shape to fit the substrate more snugly. This induced fit is essential for stabilizing the enzyme-substrate complex and facilitating the catalytic reaction.