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Catalysts and Enzymes: Role, Types, and Mechanisms, Exams of Biotechnology

An introduction to catalysts, focusing on their role in increasing reaction rates and their classification into homogeneous, heterogeneous, and enzyme catalysts. The text also covers acid-base catalysis and the specific example of carbonic anhydrase. Additionally, it discusses the classification of catalysis and the differences between homogeneous and heterogeneous catalysts.

Typology: Exams

2020/2021

Uploaded on 05/09/2021

madhuri-rayadurgam
madhuri-rayadurgam 🇮🇳

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INTRODUCTION
Catalysts are substances that can be added to a reaction to increase the reaction rate without
getting consumed in the process. They usually work by
Lowering the energy of the transition state, thus lowering the activation energy, and/or
Changing the mechanism of the reaction. This also changes the nature (and energy) of the
transition state.
Catalysts are everywhere! Many biochemical processes, such as the oxidation of glucose, are
heavily dependent on enzymes, proteins that behave as catalysts.
Other common kinds of catalysts include acid-base
catalysts and heterogeneous (or surface) catalysts.
Catalytic proteins:
Enzymes are the proteins that regulate biochemical processes. They are often called catalysts,
because they function to lower the activation energy of the reaction and thereby increases the
rate of the reaction. ... Enzymes are biological catalysts or assistants.
A catalyst is a substance that can be added to a reaction to increase the reaction rate
without getting consumed in the process.
Catalysts typically speed up a reaction by reducing the activation energy or changing the
reaction mechanism.
Enzymes are proteins that act as catalysts in biochemical reactions.
Common types of catalysts include enzymes, acid-base catalysts,
and heterogeneous (or surface) catalysts.
Example: Carbonic anhydrase
The enzyme carbonic anhydrase catalyzes the reversible reaction of carbon dioxide CO2 and
water H2O to form carbonic acid. When the concentration of CO2 in the body is too high,
carbonic anhydrase catalyzes the following reaction:
By regulating the concentration of carbonic acid in the blood and tissues, the enzyme is able to
keep the pH balanced in the body.
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INTRODUCTION

Catalysts are substances that can be added to a reaction to increase the reaction rate without getting consumed in the process. They usually work by Lowering the energy of the transition state, thus lowering the activation energy, and/or Changing the mechanism of the reaction. This also changes the nature (and energy) of the transition state. Catalysts are everywhere! Many biochemical processes, such as the oxidation of glucose, are heavily dependent on enzymes , proteins that behave as catalysts. Other common kinds of catalysts include acid-base catalysts and heterogeneous (or surface ) catalysts. Catalytic proteins: Enzymes are the proteins that regulate biochemical processes. They are often called catalysts , because they function to lower the activation energy of the reaction and thereby increases the rate of the reaction. ... Enzymes are biological catalysts or assistants.  A catalyst is a substance that can be added to a reaction to increase the reaction rate without getting consumed in the process.  Catalysts typically speed up a reaction by reducing the activation energy or changing the reaction mechanism.  Enzymes are proteins that act as catalysts in biochemical reactions.  Common types of catalysts include enzymes , acid-base catalysts , and heterogeneous (or surface ) catalysts. Example: Carbonic anhydrase The enzyme carbonic anhydrase catalyzes the reversible reaction of carbon dioxide CO2 and water H2O to form carbonic acid. When the concentration of CO2 in the body is too high, carbonic anhydrase catalyzes the following reaction: By regulating the concentration of carbonic acid in the blood and tissues, the enzyme is able to keep the pH balanced in the body.

Carbonic anhydrase is one of the fastest known enzymes, with reaction rates between 104

  • (^106) reactions per second. This is even more amazing compared to the uncatalyzed reaction, which has a rate of ~0.2 reactions per second. That is a ~10^5 -10^7 increase in rate!! The following diagram shows an energy diagram for the reaction between carbon dioxide and water to form carbonic acid. The reaction with catalyst is indicated with a blue line, and the uncatalyzed reaction is indicated with a red line. Diagram of a catalytic reaction A ribbon diagram of human carbonic anhydrase II. Classification: Catalysis may be classified as either homogeneous or heterogeneous. A homogeneous catalysis is one whose components are dispersed in the same phase (usually gaseous or liquid) as the reactant's molecules. A heterogeneous catalysis is one where the reaction components are not in the same phase. Enzymes and other biocatalysts are often considered as a third category. Similar mechanistic principles apply to heterogeneous, homogeneous, and biocatalysis.

Acid-base catalysis

In acid catalysis, the catalyst is usually a H+. In base catalysis, the catalyst is usually an OH−ion. An example of a reaction that can be catalyzed by acid is the hydrolysis of sucrose, also known as table sugar. Sucrose is a combination of two simpler sugars (or monosaccharides ),

Enzymes: The word enzyme is formed from two Greek words: en means inside and zyme, which means yeast i.e., the word enzyme means inside yeast.

  • There are many methods for naming enzymes: 1- The old trivial name as pepsin and trypsin. 2- The name of substrate and the suffix – ase added to it as lactase acting on lactose and sucrase acting on sucrose. 3- Two words, one for the substrate and the other for the type of reaction e.g. succinate dehydrogenase, pyruvate decarboxylase and glutamine synthetase.
  • Enzyme Code (EC): Each enzyme has a numerical code which is formed of four digits separated by dots: The first digit denotes the class (reaction type) of the enzyme. The second digit denotes the functional group upon which the enzyme acts. The third digit denotes the coenzyme. The fourth digit denotes the substrate. For example 1.1.1.1 enzyme, 1 means oxidoreductase, 1.1 means that the functional group is hydroxyl group (-OH), 1.1.1 means NAD is the coenzyme and 1.1.1.1 means alcohol. So, 1.1.1.1 means alcohol dehydrogenase enzyme. Enzymes: “The biological catalysts”
  • They are organic thermo-labile catalysts that increase the chemical reaction without change.
  • They accelerate the rate of chemical reaction without being consumed in the reaction. Chemical Nature of Enzyme

Chemical Nature of Enzymes : All enzymes are protein in nature except ribozymes (RNA in nature). What is the difference between an enzyme and a protein? All enzymes are proteins except some RNAs • not all proteins are enzymes Protein enzymes are classified into 2 types: 1- Simple Protein enzymes: They are formed of protein only. 2- Complex (conjugated) Protein : They are formed of protein part and non protein part. Enzymes formed of two parts: 1) Protein part: called apoenzyme 2) Non- protein: called cofactor

  • The whole enzyme is called holoenzyme. Nature of enzyme: The cofactor may be coenzyme or prosthetic group
  • Coenzyme: Is organic, thermo-labile, loosely attached to enzyme.
  • They are mainly vitamin B derivatives e.g. FAD, NAD.
  • Prosthetic group: Is inorganic, thermo-stable, firmly attached to enzyme.
  • They are usually metal ions e.g. Ca, Zn Substrate : reactant which binds to enzyme enzyme-substrate complex: temporary association. Product : end result of reaction.
  1. Products released and 5. Enzyme recycled