Login with Facebook

What are Enzymes and how do they work

Enzymes are biological catalysts of a protein nature, without which life could not exist. Only a small group of enzymes are made up of RNA molecules, called ribozymes, which come into play in some processes such as protein synthesis and splicing of messenger RNA in eukaryotic cells.

Enzymes preside over the many metabolic reactions of a living organism, regulating the exchange of energy with the external environment.

Due to enzymes, it is possible to digest food, recover energy in the bonds of biomolecules in the form of ATP, usable for all endergonic processes, which are also catalyzed by enzymes such as the biosynthesis of macromolecules from simpler organic substances.


The enzymes can accelerate the reactions by a factor between 105 and 107, showing a catalytic power and specificity often far superior to inorganic and synthetic catalysts. The central role played by enzymes for the survival of living organisms explains why many genetic diseases that alter the functionality of many enzymes give rise to pathological conditions, even quite serious ones. The evaluation of the number of certain enzymes in the blood and other tissues is a useful diagnostic tool, for example, liver and cardiac dysfunctions. Furthermore, the action of many drugs is based on the interaction with enzymes, modulating their activity in various ways.

Nomenclature of enzymes

The name of the enzymes derives from the substrate or phrase that describes its activity, adding the suffix -asi. In some cases, the names of the enzymes are based on a given function, before the specific catalyzed reaction was discovered, such as for the digestive enzymes pepsin and trypsin or lysozyme. Often many enzymes are indicated by multiple names, which can be confusing.


To overcome possible ambiguities, the international system of nomenclature and classification of enzymes provides six classes, in turn, divided into subclasses.

Each enzyme is indicated by a systematic name that describes the catalyzed reaction and by a series of four numbers, the first of which indicates the class, the second the subclass.

The structure of enzymes

Enzymes are large proteins, often with a quaternary structure, capable of specifically binding one or more reacting substances, called substrates, catalyzing their conversion into others.

In some cases, the enzymes carry out the catalysis autonomously; they require the intervention of cofactors, additional non-protein components.


The cofactors can be metal ions, such as Fe2 +, Mg2 +, Mn2 +, or Zn2 +, or complex organic molecules called coenzymes, such as NAD, FAD, biotin, coenzyme A and many others.

If metal ions or a coenzyme are stably covalently linked to enzymes, they are called prosthetic groups.

The set of the protein component and cofactors of an enzyme is called a holoenzyme. The only protein part is called apoenzyme or apoprotein.

The binding of substrates to enzymes

The bonding of the substrates takes place in pockets of the enzymes called active sites, where the amino acid residues present to ensure the specificity of the bond with the substrates and the catalysis mechanisms necessary to make the reaction take place. Weak interactions mainly ensure specificity.

The interaction between the substrate and the active site has been classically described with the key-lock model, proposed by Fisher in 1894.

However, if the active site perfectly adapted to the substrate, from an energy point of view, the transformation into a different compound would not be more advantageous, because it would compromise the stability of the enzyme-substrate interaction.

The catalytic action of the enzymes

As catalysts, enzymes intervene in reactions without being consumed, lowering their activation energy, often remarkably high considering that most biomolecules are stable in the cellular environment, and conversion to other compounds would be non-spontaneous or even unlikely.

Activation energy is an energy barrier between reagents and products that prevents the reaction from proceeding in a period compatible with the needs and survival of the cell and a living organism.

An enzyme can lower the activation energy by creating a favorable environment that makes the reaction energetically favored and achievable in a short time, in the order of milliseconds.


The mechanisms by which the enzyme favors the lowering of the activation energy are basically three. It reduces the random movements of the reacting molecules that are immobilized on the surface of the enzyme to favor their correct orientation for the purpose of the reaction.

Secondly, the interaction with the enzyme removes the substrate from the solvation halo created by the water molecules, which, due to hydrogen bonds, stabilizes most of the biological molecules in the cells.

Thirdly, the enzyme adopts catalysis mechanisms that make the breakage and formation of chemical bonds energetically possible, processes necessary in the course of a reaction to generate new substances from one or more initial reagents.

Catalysis mechanisms

The catalysis mechanisms are the strategies implemented by the enzymes in the breaking and bonding processes that take place during the reaction.

Among the best-characterized mechanisms are:

• Acid-base catalysis;

• Covalent catalysis;

• Catalysis by metal ions.

Acid-base catalysis consists in the transfer of H + from the amino acid residues of the active site of the enzyme or vice versa, creating intermediates whose transformation into products occurs more easily.

Covalent catalysis presupposes the formation of a transient covalent bond between the substrate and the protein component of the enzyme or its coenzyme.

Some enzymes have metal ions as a cofactor, whose positive charges generally have the function of orienting the substrate and stabilizing any charges.

Enzymatic kinetics

Most enzymes show a hyperbolic relationship between the substrate concentration and the speed of the catalyzed reaction, mathematically described by the Michaelis-Menten equation.


The achievement of the maximum speed is due to the saturation of the active sites of the enzyme molecules. Only by increasing the amount of enzyme is it possible to obtain a further increase in speed, also in this case destined to reach a maximum value when there are no more active sites available to bind the substrate molecules.


The Michaelis-Menten equation includes the constant Km (Michaelis constant)Enzymes, specific for each catalyzed reaction. It represents the concentration of substrate at which half of the maximum speed is reached and can be considered a measure of the affinity of the enzyme for the substrate.


Comments




Send Comment

Need a custom
essay?

We will write it for you.
Order now

Free Essay Examples

Free essays:

An ultimate guide about biochemical reactions
Analysis methods of Transport through biological membranes
A Comprehensive Introduction to the Mona Lisa
An ultimate guide about Biomaterials
Big data analysis in evolutionary biology
Brain-Computer Interface systems with EEG signals
Biochemistry of neurotransmitter
Bipolar disorder: Symptoms, causes, diagnosis and treatment
Cellular excitability
Characterization of biological tissues, biomaterials
Characteristics of the byzantine architecture
Commonly Confused Words: Part 2
Dynamic Systems Modeling with Machine Learning
Digital Imaging: What Is It?
Different forms of dance you should know about
Data Science: Fundamental tools for data analysis
Everything you need to know about enzymatic kinetics
Electromagnetic exposure effects on human organs
Effects of Different Environmental Factors on Artworks
Entrepreneur trends to know about
Famous Ballet Forms
Four postulates of natural selection
Famous African American literature authors
Film styles and the types of styles for shooting a film
Importance of online journalism
Importance of 3d Modelling in Architecture
Introduction to Utilitarianism
Identity theft: what to do?
Kinetic models in biology and Related fields
Know about the different forms of traditional African dances
Know about the history of science
Latest technology trends
Mass transport in a biological system
Major themes in ancient Egyptian art
Major healthcare trends
Misconceptions About the Word “Introvert”
Nonlinear Dynamics in Biology & Biomedicine
NLS (Nonlinear System) - Revolutionary system in diagnostic medicine and therapy
Neural networks: what they are and what they are for
Nuclear fusion: What it is and how it works?
Role of Homeostasis in Human Physiology
Role of a digital artist
Role of gender studies
Risk management, meaning, and importance for companies
Systems biology - An understanding the functioning of biological systems
Self-assembly for biological systems
School of American Ballet
Schizophrenia - a rare psychiatric illness | Essay
The impact of the technological innovations in medicine
The Defense mechanisms against infections
Tips for writing a great thesis statement
The Modeling of Biological Systems
Understand the importance of investigative journalism
Urban planning in the US
Understanding the sociology of Race & Ethnicity
Various theoretical perspectives of sociology
Women empowerment in modern generation
What Makes a Good Leader
What is biopolymers?
What is the cytoplasm and its function?
4 Facts about Origin of Mathematics!
5 techniques to create an animation
13 Best colleges for political science in the world
3d Model Of Building
All you need to know about the ACA Code of ethics
Architecture and Democracy: An Introduction
Architecture and Democracy: Democratic Values
Architecture and Democracy: Democratic Procedures
All You Need to Know About a Synthesis Essay
An essential guide to understanding Film Theory
Application of Artificial Intelligence in Cyber Security
Applications of electrical engineering
Augmented reality: what it is, how it works, examples
Advantages And Disadvantages Of Social Networking
All you need to know about Cryptography
Applications of astrophysical science
All you need to know about architecture engineering
Applications of geological engineering
Artificial intelligence and medicine: an increasingly close relationship
An insight into Computational Biology
ACA code of conduct
A Rose for Emily
Applications of Mathematics in daily life
Architecture mistakes to avoid
All you need to know about Toxicology
All you need to know about Holistic Medicine
All you need to know about linguistics
An introduction to Linguistics and its subfields
All you need to know about Anxiety disorder
All you need to know about Drones
A Brief Insight into Political Science
Assumptions related to feminism
All you need to know about Byzantine emperors
All you need to know about labour economics
An insight into xenobots -the first-ever robots
An ultimate guide about Biomaterials
A Comprehensive Introduction to the Mona Lisa
Analysis methods of Transport through biological membranes
An ultimate guide about biochemical reactions
How to Write a Personal Essay
Housing Needs in America
How to Write a Description Essay
How to Create an Excellent Scholarship Essay?
How to write a cause and effect essay
How to Hire the Best Essay Writing Service Provider?
How to Write a College Application Essay?
How to get the most out of your English lectures
How to write Expository Essay
How to succeed in your psychology class?
How to Write an Academic Essay in the Shortest Time?
History of Journalism
How Different Sectors are Using Artificial intelligence (AI)
How to write an informative essay
How to deliver persuasive essays?
How to Give a Convincing Presentation
How to write an essay on leadership?
Historical Art Still Around Today
Humanoid robot: what it is, how it works and price
History of Chemistry
Healthcare Advanced Computer Power: Robotics, Medical Imaging, and More
Healthcare AI: Game Changers for Medical Decision-Making and Remote Patient Monitoring
How to understand different types of English
How to Cope with Chronic Pain
How African American choreographers and dancers have influenced American dance
How mobile robot can do in logistics or in production
How To Become a Successful Entrepreneur
History of the Philosophy of Feminism
How is the climate changing?
How to Track Your Content Marketing ROI
How to Gun control In the USA?
Historical and contemporary role of labour in the modern world
How breast cancers are classified?
How the cells of our body communicate?
How the Lymphatic System Works?
How Digestive System Works
How to complete your capstone projects effectively?
How to write a research project
Healthcare technologies that help patients with better self-management
How to choose the topic of the senior capstone project