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.

Outlines

00:00

🧬 Enzymes: Catalysts of Life's Chemical Reactions

Enzymes are biological catalysts, primarily proteins or RNA, that accelerate biochemical reactions by lowering the activation energy required for these processes to begin. Discovered by Anselme Payen in 1833, they exhibit remarkable specificity, binding only to particular substrates. The active site of an enzyme, characterized by a unique arrangement of amino acids, is where substrate binding and reaction occur. Some enzymes also contain cofactors, which can be metal ions, vitamins, or permanent components, that assist in their catalytic function. The enzyme-substrate complex can be represented by two models: the Lock and Key Hypothesis, which suggests a perfect fit between the enzyme and substrate, and the Induced Fit Hypothesis, which allows for a dynamic shape change upon substrate binding. Environmental factors such as temperature and pH can significantly affect enzyme function, with optimal conditions being crucial for maintaining their structure and activity.

05:01

🚫 Inhibitors: Regulating Enzyme Activity

Inhibitors are substances that negatively impact enzyme activity by interfering with the active site or the overall enzyme structure. Competitive inhibitors directly occupy the active site, preventing substrate binding, thus reducing the reaction rate. In contrast, non-competitive inhibitors bind to a different part of the enzyme, causing a conformational change that impairs the enzyme's ability to bind its substrate. This summary highlights the importance of understanding enzyme regulation in biochemical processes, as inhibitors can be crucial in controlling metabolic pathways and are also the basis for many pharmaceutical drugs.

Keywords

💡Enzymes

Enzymes are biological catalysts that significantly speed up biochemical reactions in the human body without being consumed in the process. They are crucial for understanding the video's theme as they are the central focus. The script mentions that enzymes can be proteins or RNA and are highly selective, binding to specific substrates to lower the activation energy required for reactions to occur.

💡Chemical Reactions

Chemical reactions are processes that lead to the transformation of substances into different products. In the context of the video, these reactions are fundamental to the functioning of the human body and are controlled by enzymes. The script discusses how enzymes facilitate these reactions by interacting with substrates.

💡Substrates

Substrates are the specific molecules that enzymes act upon to catalyze a chemical reaction. The script explains that enzymes are selective, binding to their respective substrates at the active site, which is integral to the enzyme's function and the video's main message.

💡Activation Energy

Activation energy is the minimum amount of energy required to initiate a chemical reaction. The video script describes how enzymes lower this energy threshold, making reactions proceed more efficiently, which is a key concept in understanding enzyme function.

💡Active Site

The active site is a specific region within an enzyme where the substrate binds and the chemical reaction takes place. The script emphasizes its uniqueness, shaped by the arrangement of amino acids, which is vital for the enzyme's specificity and function.

💡Cofactors

Cofactors are non-protein components that assist enzymes in their catalytic activity. The video script mentions cations, organic molecules like vitamins, and prosthetic groups as types of cofactors, which are essential for the enzyme's function and the overall theme of enzyme action.

💡Holoenzyme

A holoenzyme is a complete enzyme system consisting of an inactivated enzyme (apoenzyme) and its coenzyme. The script explains this concept to illustrate the full potential of an enzyme when combined with its necessary cofactor, which is central to the video's educational content.

💡Apoenzyme

An apoenzyme is the protein part of an enzyme that is not yet active and requires a coenzyme to function. The video script uses this term to describe the inactive state of the enzyme before it combines with its cofactor to form a holoenzyme.

💡Lock and Key Hypothesis

The Lock and Key Hypothesis is a model that describes how an enzyme's active site and substrate fit together perfectly, like a key in a lock. The script uses this model to explain the enzyme's specificity and the initial understanding of enzyme-substrate interaction.

💡Induced Fit Hypothesis

The Induced Fit Hypothesis suggests that the enzyme's shape changes upon substrate binding, allowing a tighter fit. The video script presents this as an advanced model of enzyme action, emphasizing the dynamic nature of enzyme-substrate interactions.

💡Environmental Effects

Environmental effects refer to external factors such as temperature and pH that can influence enzyme function. The script discusses how these factors can alter the enzyme's active site, affecting its ability to bind substrates and catalyze reactions, which is crucial for understanding the conditions required for optimal enzyme activity.

💡Inhibitors

Inhibitors are substances that reduce or stop enzyme activity in biochemical reactions. The video script differentiates between competitive and non-competitive inhibitors, explaining how they interfere with the enzyme's active site or overall structure, which is an important aspect of understanding enzyme regulation.

Highlights

Enzymes are proteins or RNA that catalyze biochemical reactions by modifying specific substrates.

French Chemist Anselme Payen discovered enzymes in 1833, identifying them as the driving force behind chemical reactions.

Enzymes exhibit high specificity, binding and modifying only certain substrates.

Enzymes function by lowering the activation energy required for a reaction to begin.

The active site of an enzyme is where substrate binding and reaction take place, characterized by a unique arrangement of amino acids.

Cofactors, including cations, organic molecules, and prosthetic groups, are essential for some enzymes' catalytic activity.

Apoenzyme refers to the inactive enzyme protein, which requires a coenzyme to form the active holoenzyme.

The Lock and Key Hypothesis is the foundational model explaining enzyme-substrate interactions.

The Induced Fit Hypothesis suggests that enzymes change shape upon substrate binding to achieve a tighter fit.

Environmental factors such as temperature and pH significantly affect enzyme function by influencing the active site.

Optimal enzyme function occurs at a body temperature of 37°C, with deviations causing denaturation.

pH fluctuations can denature enzymes by affecting the acidic or basic nature of amino acids in the active site.

Enzyme concentration influences reaction rates, with diminishing returns beyond a certain concentration.

Substrate concentration increases reaction rates up to a saturation point where additional substrate does not affect the rate.

Inhibitors are substances that reduce or stop enzyme activity by blocking or distorting the active site.

Competitive inhibitors occupy the active site, preventing substrate binding, while non-competitive inhibitors distort enzyme shape.

Transcripts

What are Enzymes?

Enzymes

Human body is a product of different chemical reactions

and processes.

But what controls these reactions?

In 1833,

a French Chemist Anselme Payen,

was the first to discover the vital force

that drove these reactions and named it “Enzyme”.

Enzymes are substances,

proteins or in some cases ribonucleic acid (RNA),

that speed up a biochemical reaction

by modifying specific substances called substrates.

Enzymes are supremely selective

in who they bind to and modify,

hence their “specificity”.

Mode of Action

Easier said,

but how does a tiny enzyme speed up a chemical reaction?

The answer to this is simple.

Enzymes perform this critical task

by lowering a reaction's activation energy,

that is, the amount of energy needed for the reaction to begin.

Enzymes bind to their substrates,

hold them in such that chemical bond-breaking

and bond-forming processes take place more easily.

Enzymes have a specific place in them called “Active Site”

where the substrate binds

and real time action takes place.

Active site has a specific size,

shape and chemical behavior rendered to it

by specific arrangement of amino acids.

Thanks to these amino acids,

an enzyme's active site is unique only to a particular substrate.

In addition to the active site,

many enzymes consist of a non-protein part called “Cofactor”.

Cofactors may be:

Cations: Positively charged metal ions (activators),

bound temporarily to the active site to “activate” the enzyme.

Organic molecules: Vitamins or vitamin products (coenzymes),

that join enzyme-substrate complex temporarily.

Prosthetic groups: Permanently enzyme bound.

Many enzymes only perform their catalytic role when associated a coenzyme.

An in activated enzyme (protein)

along with its coenzyme (non-protein)

makes up a system called holoenzyme.

To add to the complexity,

scientists termed this inactivated enzyme as apoenzyme

and therefore the equation becomes:

Holoenzyme=Apoenzyme+ Coenzyme

Models of Enzyme Action

Lock and Key Hypothesis

This is the simplest model to represent how an enzyme works.

The substrate simply fits into the active site

to form a reaction intermediate

just like the key fits in its specific lock.

The shape isn’t changed here,

rather the structure of substrate

absolutely compliments the structure of the enzyme,

like puzzle pieces.

Induced Fit Hypothesis

In this model,

the enzyme, upon binding of substrate, changes shape.

The matching between an enzyme's active site and the substrate

isn’t just like two puzzle pieces fitting together,

rather the enzyme changes shape

and binds to its substrate even more tightly.

This fine-tuning of the enzyme to “fit” the substrate is called induced fit.

Environmental Effects on Enzyme Function

Active sites are very sensitive.

They sense even the slightest change in the environment

and respond accordingly.

Some of the factors that affect the active site

and consequently enzyme function include:

Temperature

The suitable temperature for enzymes to function properly is 37°C.

Increasing or decreasing the temperature above 37°C

affect chemical bonds in the active site,

making them less suited to bind substrates.

Higher temperatures denature enzymes.

pH

Amino acids present in the active site are acidic or basic.

Fluctuation in pH can affect these amino acids

making it hard for substrates to bind.

Extreme pH values can denature enzymes.

Enzyme Concentration

Increasing enzyme concentration will increase the rate of reaction,

as more enzymes will be available to bind with substrates.

However,

after a certain concentration,

any increase will have no effect on the rate of reaction.

Substrate Concentration

Increasing substrate concentration increases the rate of reaction.

This is because more substrate molecules

will be colliding with enzyme molecules,

so more product will be formed.

But again,

this effect is valid up to a certain concentration.

Inhibition of Enzyme Activity

Some evil substances, called “inhibitors”,

reduce or even stop the activity of enzymes

in biochemical reactions.

They either block or distort the active site,

thus inhibiting the reaction.

Based on this,

there are two types of inhibitors given below:

Competitive Inhibitors:

Occupy the active site

and prevent a substrate molecule from binding to the enzyme.

Non-competitive Inhibitors:

Attach to parts of the enzyme,

other than the active site,

to distort the shape of an enzyme.