Name: competitive vs noncompetitive inhibitors
Uploaded: 2025-10-23T11:48:34.000Z
Duration: 1 min 30 s
Channel: JoVE

- [Instructor] Ciertas
sustancias químicas específicas

pueden regular la acción de las enzimas

mediante la inhibición o
bloqueo de sus funciones.

Existen dos tipos de
inhibidores enzimáticos,

los competitivos y los no competitivos.

La la inhibición competitiva
es bastante similar

al sustrato específico de la enzima

que puede adherirse al sitio activo

y evitar que el sustrato de adhiera.

Esta acción logra disminuir el número

de enzimas disponibles
para adherirse al sustrato.

Por el contrario, la
inhibición no competitiva

se adherirá lejos del sitio
activo, pero aún tendrá efecto

porque, por ejemplo, modificará
la forma de la enzima

y reducirá en gran medida la posibilidad

del sustrato de adherirse al sitio activo,

logrando que la enzima
funcione correctamente.

Además, estos inhibidores
afectan de manera diferente

la velocidad de una reacción química.

En comparación con una velocidad
normal de reacción química,

la reacción que incluya los
inhibidores competitivos

tardará más en llegar a la
velocidad máxima de reacción

y necesitará de más sustrato para hacerlo,

ya que debe haber suficiente sustrato

para lograr evitar que el inhibidor

tenga acceso a los sitios activos.

Por el contrario, un
inhibidor no competitivo

no permitirá que la reacción
llegue a la velocidad máxima

porque el número de enzimas disponibles

para adherirse es reducido.

Goh, Ee Teng y Marsha Y. Morgan. "Farmacoterapia para la dependencia del alcohol: el por qué, el qué y el por qué". Farmacología y Terapéutica Alimentaria 45, no. 7 (2017): 865-882. [<a href="https://doi.org/10.1111/apt.13965">Fuente</a>]

inhibición enzimática

Enzyme Inhibition

Los inhibidores son moléculas que reducen la actividad enzimática uniéndose a la enzima. En una célula que funciona normalmente, las enzimas están reguladas por una variedad de inhibidores. Las drogas y otras toxinas también pueden inhibir las enzimas. Algunos inhibidores se unen al sitio activo de la enzima, aunque otros inhiben la actividad enzimática uniéndose a otros sitios de la estructura de la proteína. Los inhibidores competitivos ocupan el sitio activo de las enzimas, haciéndolas incapaces de acomodarse al sustrato. Sin embargo, concentraciones suficientemente altas del sustrato pueden superar al inhibidor; como resultado, los inhibidores competitivos reducen la velocidad de reacción inicial de la enzima, pero no afectan la velocidad máxima de la enzima. Un ejemplo de inhibidor competitivo es el fármaco disulfiram, utilizado para tratar el alcoholismo crónico. Cuando se ingiere alcohol, normalmente se convierte en acetaldehído, que luego se convierte en acetil coenzima A mediante la acetaldehído deshidrogenasa.El disulfiram se une y ocupa el sitio activo del acetaldehído deshidrogenasa, lo que hace que la enzima no pueda realizar esta conversión. Como resultado, un paciente que toma disulfiram comienza inmediatamente a experimentar síntomas similares a los de la resaca, como dolor de cabeza, lo que disminuye el consumo de alcohol. Los inhibidores no competitivos se unen a distintos sitios de la enzima, lejos del sitio activo. Estos se denominan sitios alostéricos y cuando las moléculas se unen a ellos, la forma del sitio activo cambia, de modo que la enzima tiene una menor afinidad por el sustrato. Debido a que los inhibidores no competitivos no ocupan el sitio activo, la presencia de sustrato adicional no puede superar la inhibición no competitiva y la enzima no puede alcanzar su velocidad de reacción máxima. La unión covalente entre un inhibidor y una enzima suele ser irreversible, como en el caso de algunas toxinas. La mayoría de los inhibidores reguladores normalmente activos en la célula interactúan con las enzimas mediante interacciones débiles. Este tipo de unión es reversible y útil para la regulación de procesos metabólicos. La exploración de nuevas moléculas para inhibir de forma competitiva y no competitiva las enzimas que regulan el crecimiento celular en el cáncer es un área de investigación activa.

Inhibición enzimática

Los inhibidores son moléculas que reducen la actividad de la enzima al unirse a la enzima. En una célula que funciona normalmente, las enzimas están reguladas por una variedad de ...

Education

Educación

JoVE Core

Biology

Biología

Cellular Processes

Procesos celulares

Metabolism

Metabolismo

KEY TERMS AND CONCEPTS

TÉRMINOS Y CONCEPTOS CLAVE

competitive vs noncompetitive inhibitors

Enzyme inhibitors are molecules that reduce enzyme activity by binding to enzymes. Cells use these inhibitors to help regulate normal enzyme function. Drugs and toxins can also block enzymes and change how they work.

Some inhibitors bind at the active site, which is the part of the enzyme where the substrate normally fits. Competitive inhibitors do this by occupying the active site and preventing the substrate from binding. If the substrate concentration becomes high enough, it can outcompete the inhibitor. For that reason, competitive inhibitors slow the initial reaction rate but do not change the enzyme’s maximum rate.

A clear example is disulfiram, a drug used to treat chronic alcoholism. Alcohol is normally converted to acetaldehyde and then to acetyl coenzyme A by acetaldehyde dehydrogenase. Disulfiram binds to the active site of acetaldehyde dehydrogenase and blocks this conversion. This causes hangover-like symptoms, such as headache, and helps decrease alcohol consumption.

Noncompetitive inhibitors bind at a different part of the enzyme. These binding sites are called allosteric sites. When a noncompetitive inhibitor binds, it changes the shape of the active site and lowers the enzyme’s affinity for the substrate. Extra substrate cannot overcome this effect, so the enzyme cannot reach its maximum reaction rate.

Some inhibitors form covalent bonds with enzymes. This binding is usually irreversible, as with some toxins. Most inhibitors that regulate metabolism in cells bind more weakly. That weak binding is reversible and helps control metabolic processes. Researchers also study enzyme inhibitors as possible treatments for cancers that involve cell growth.

Competitive vs Noncompetitive Inhibitors

what is metabolism?

Metabolism, Energy, and Cell Reactions

Metabolism is the set of chemical reactions that happen in a cell. It includes anabolism, which builds molecules, and catabolism, which breaks them down. These reactions help cells manage energy and keep life processes running. Cells use metabolism to turn food into energy, make cell parts, and remove waste products. Food stores potential energy in the bonds between atoms. Catabolic pathways break large food molecules into smaller ones and release that energy. Anabolic pathways use that energy...

first law of thermodynamics

Energy Flow in a Food Web

Energy flow in a food web shows the First Law of Thermodynamics in action. Energy cannot be created or destroyed. It can only change form as it moves through living things and the environment. Sunlight is the starting point. Plants capture radiant energy from the sun during photosynthesis and turn it into chemical energy stored in complex carbohydrates. At the same time, oxygen is released into the atmosphere. Herbivores eat the plants and use those sugars during digestion. The energy is...

second law of thermodynamics

Entropy in Food Web Energy Flow

The Second Law of Thermodynamics explains why entropy increases as energy moves through a system. Entropy means the amount of disorder in a system. Each time energy is transferred or transformed, some energy is lost as unusable heat. That heat can raise the motion of nearby molecules for a short time and make the surroundings less ordered and more random. This idea also appears in a food web. Primary producers, such as plants, take in energy from the sun and make food. During this process,...

kinetic energy

Motion as a Source of Energy

Kinetic energy is the energy of motion. It appears when an object is moving and can do work or cause change. A waterfall is one clear example. Water behind a dam has potential energy, but when it rushes downward, that moving water has kinetic energy. When the water reaches the bottom and stops moving, its energy can become potential energy again. Kinetic energy also shows up in living systems. Plants absorb light particles, called photons, which move very fast and help create chemical energy...

potential energy

Stored Energy in Motion and Bonds

Stored energy in motion and bonds is called potential energy. It depends on the structure of an object or the position of matter in space. Raising a kettlebell changes its location and increases its potential energy. A stretched rubber band also stores potential energy, which can later change into kinetic energy. Chemical bonds between atoms hold another form of stored energy called chemical energy. These bonds involve attractive forces, and that energy can change into other forms during a...

free energy

Gibbs Free Energy in Chemical Reactions

Gibbs free energy is a measure of useful energy that can be taken from a chemical reaction to do work. It is written as G and named for scientist Gibbs, who discovered it. This energy is what remains after entropy is considered. A reaction can either take in energy or release it. Reactions that absorb energy are called endergonic reactions. Reactions that release energy are called exergonic reactions. The direction of energy flow helps show which type of reaction is happening. Plants carry...

activation energy

How Catalysts Lower Reaction Barriers

Activation energy is the minimum energy a chemical reaction needs to keep going. When the activation energy is higher, the reaction usually happens more slowly. Adding heat can speed the reaction because molecules move faster and collide more often. As reactants collide, bonds break and the reaction moves through an uphill phase. That step creates the transition state, which is an unstable, high-energy state of the reactants. After that, new bonds form, products appear, and free energy is...

hydrolysis of atp

ATP Breakdown and Energy Release

ATP breakdown releases energy for cell work. Adenosine triphosphate, or ATP, can lose one or two phosphate groups when water is added. This hydrolysis reaction is exergonic, which means it releases energy that the cell can use. When one phosphate group is removed, ATP becomes ADP, or adenosine diphosphate. Inorganic phosphate is also released. ADP can then be hydrolyzed again to form AMP, or adenosine monophosphate, after a second phosphate group is removed. ATP has a clear structure. It is...

phosphorylation

Phosphorylation and Protein Control

Phosphorylation helps control how proteins work in cells. It is the addition or removal of phosphate groups, and it is the most common chemical change that regulates cellular processes. These changes can alter a protein’s structure, activity, stability, location inside the cell, and interactions with other proteins. During phosphorylation, protein kinases move the terminal phosphate group from ATP to a specific amino acid side chain on a target protein. The amino acids most often...

induced-fit model

How Enzymes Adjust to Their Substrates

Enzymes speed up many chemical reactions in cells. They are biological catalysts, so they increase reaction speed without being consumed or permanently changed. They do this by lowering the activation energy needed to turn reactants into products. Enzymes are proteins that usually work by binding to a substrate, which is the reactant molecule they act on. They show substrate specificity, meaning they bind only certain substrates. This specificity depends mainly on the shape and chemical...

enzyme kinetics

Substrate Effects on Enzyme Rates

Enzyme kinetics examines how enzymes change the rate of a reaction. Enzymes speed reactions by lowering the activation energy of the reactants. The reaction rate is the speed at which an enzyme turns reactants into products, and it can be affected by several factors, including the number of available reactants. Scientists often study enzyme kinetics in a test tube with a fixed amount of enzyme. When more substrate, or reactant, is added, the reaction rate increases because the enzyme can make...

enzyme inhibition

Enzyme inhibitors are molecules that reduce enzyme activity by binding to enzymes. Cells use these inhibitors to help regulate normal enzyme function. Drugs and toxins can also block enzymes and change how they work. Some inhibitors bind at the active site, which is the part of the enzyme where the substrate normally fits. Competitive inhibitors do this by occupying the active site and preventing the substrate from binding. If the substrate concentration becomes high enough, it can outcompete...

feedback inhibition

How Cells Control Product Buildup

Cells use enzymes to run biochemical reactions and make the products they need. These reactions are happening constantly, and enzymes speed them up so they happen fast enough to matter. Enzyme activity also has to be regulated. Cells need the right amounts of starting materials, intermediate metabolites, and final products. If these substances build up too much or drop too low, the cell can be harmed. That is why cells use control systems to keep metabolic levels balanced. One important...

allosteric regulation

Allosteric Control of Enzyme Speed

Allosteric control changes enzyme speed when a molecule binds to a site other than the active site. That alternate binding spot is called an allosteric site. An enzyme can have more than one allosteric site. This type of control can raise or lower enzyme activity. Many enzymes with allosteric control are metabolic enzymes. They help with the breakdown or the building of specific molecules in cells. In allosteric inhibition, the effector molecule causes a shape change that lowers the enzyme's...

cofactors and coenzymes

Enzyme Helpers: Metals, Vitamins, and More

Enzyme helpers are needed for many enzymes to work properly. These helpers fall into two groups: cofactors and coenzymes. Cofactors are metallic ions, while coenzymes are non-protein organic molecules. Both can be tightly bound to an enzyme or attach only when the substrate binds. Cofactors are common in mature proteins, appearing in about 30% of them. They are often added as the enzyme folds and help with catalytic activity. Magnesium is one important cofactor, and it is needed by more than...

key terms and concepts

Compare competitive and noncompetitive enzyme inhibitors, including active-site binding, allosteric effects, disulfiram, and how inhibitors regulate cells.

Competitive vs Noncompetitive Inhibitors | JoVE K12

JoVE Core series brings biology to life through over 300 concise and easy-to-understand animated video lessons that explain key concepts in biology, plus more than 150 scientist-in-action videos that show actual research experiments conducted in today’s laboratories.

biology

JoVE Core Biología da vida a la biología a través de una serie con más de 300 lecciones de vídeo animadas, concisas y fáciles de entender, que explican conceptos clave de la biología, incluyendo también más de 150 vídeos de científicos en acción, que muestran experimentos reales realizados en laboratorios actuales de investigación.

myJoVE Corporation

Competitive vs Noncompetitive Inhibitors

Description

Transcript

Tags