What are Enzymes?

Summary

Enzymes, discovered by Anselme Payen in 1833, are proteins or RNA that catalyze biochemical reactions with high specificity. They lower activation energy by binding substrates at their unique active sites, composed of amino acids. Enzymes can have cofactors like metal ions or vitamins for enhanced activity. The lock and key and induced fit hypotheses explain their action. Environmental factors like temperature and pH affect enzyme function, with optimal levels at 37°C and neutral pH. Inhibitors can reduce enzyme activity by blocking or distorting the active site.

Takeaways

• 🧬 Enzymes are proteins or RNA that catalyze biochemical reactions by modifying specific substrates.
• 🔍 Enzymes are highly selective, showing specificity for the substrates they bind and modify.
• 🔄 Enzymes work by reducing the activation energy required to initiate a chemical reaction.
• 🔑 Each enzyme has a unique 'Active Site' that determines substrate specificity through the arrangement of amino acids.
• 🧲 Many enzymes require 'Cofactors', which can be metal ions, organic molecules, or permanent parts of the enzyme structure.
• 🔬 The 'Lock and Key Hypothesis' describes the enzyme-substrate interaction where the substrate fits perfectly into the enzyme's active site.
• 🔄 The 'Induced Fit Hypothesis' suggests that the enzyme's shape changes upon substrate binding to achieve a better fit.
• 🌡️ Enzyme function is sensitive to environmental factors such as temperature, with optimal activity around 37°C.
• 🌡️ pH levels also affect enzyme activity, as extreme pH values can denature enzymes and affect the active site's amino acids.
• 📈 Enzyme and substrate concentrations influence reaction rates, with diminishing returns beyond certain concentrations.
• 🚫 'Inhibitors' can reduce or stop enzyme activity by blocking or distorting the active site, with two main types being competitive and non-competitive inhibitors.

Q & A

What are enzymes and what role do they play in the human body?

Enzymes are proteins or, in some cases, ribonucleic acid (RNA) that speed up biochemical reactions by modifying specific substances called substrates. They are crucial for controlling various chemical reactions and processes in the human body.

Who discovered enzymes and when?

The French Chemist Anselme Payen discovered enzymes in 1833, referring to them as the vital force that drives biochemical reactions.

What is the term used to describe the selectivity of enzymes in binding to specific substrates?

The term used to describe the selectivity of enzymes is 'specificity'.

How do enzymes speed up a chemical reaction?

Enzymes speed up a chemical reaction by lowering the activation energy required for the reaction to begin. They bind to their substrates and facilitate the bond-breaking and bond-forming processes more easily.

What is the 'Active Site' of an enzyme?

The 'Active Site' is a specific place on an enzyme where the substrate binds and the reaction takes place. It has a unique size, shape, and chemical behavior determined by the arrangement of amino acids.

What is a 'Cofactor' in the context of enzymes?

A 'Cofactor' is a non-protein part of many enzymes, which can be cations, organic molecules like vitamins or coenzymes, or prosthetics that are permanently bound to the enzyme. They are essential for the enzyme's catalytic role.

What is the relationship between an apoenzyme and a coenzyme to form a holoenzyme?

An apoenzyme is an inactivated enzyme (protein), and a coenzyme is its non-protein part. Together, they form a system called a holoenzyme, which is the active enzyme ready to catalyze reactions.

What are the two hypotheses that describe how an enzyme works?

The two hypotheses are the Lock and Key Hypothesis, where the substrate fits into the active site without changing shape, and the Induced Fit Hypothesis, where the enzyme changes shape upon substrate binding to better fit the substrate.

How do environmental factors affect enzyme function?

Environmental factors such as temperature and pH can affect the active site of enzymes. Suitable temperature for most enzymes is around 37°C, and fluctuations in pH can make it difficult for substrates to bind.

What is the effect of enzyme concentration on the rate of a reaction?

Increasing enzyme concentration will increase the rate of reaction up to a certain point, after which any further increase will have no effect due to the saturation of substrate binding sites.

What are the two types of inhibitors that can affect enzyme activity, and how do they work?

The two types of inhibitors are Competitive Inhibitors, which occupy the active site and prevent substrate binding, and Non-competitive Inhibitors, which attach to other parts of the enzyme to distort its shape and inhibit the reaction.