Enzymes | Definition |Types |Functions | Synthesis| Biology| Physiology|

© 2021 GoogleWhat are enzymes and their  function

 

Keywords: Enzymes| Apoenzyme | Holoenzyme| Globular proteins|

 Cofactor |Prosthetic| Catalytic| isoenzyme|        

 

ALL ABOUT ENZYMES

Table of contents:

1.	Introduction
2.	Structure
3.	Mode of action
4.	Synthesis
5.	Classification
6.	Types   Ø Apoenzyme Ø Holoenzyme Ø Enzymes Ø Prosthetic group
7.	Classification
8.	Cofactors

                               

Introduction

The word enzyme comes from a Greek word meaning 'in yeast' or 'leavened.' The word enzyme was used in 1877 by Wilhelm Kuhne - a German physiologist. 

Enzymology is a branch of science that deals with the enzyme.

Enzymes act alone or with cofactors.

Synthesis

All living organisms have enzymes produced naturally in the body. Enzymes are synthesized by properly linking amino acids in the rough endoplasmic reticulum of the cell in response to coded information from the DNA.

Structure

  Enzymes are globular proteins that act as biological catalysts- biocatalysts. They have unique three-dimensional structures which are not static or rigid and change. The binding of a small molecule causes a conformational change that alters the enzyme's activity. Some enzymes have sites to bind cofactors. In addition, enzyme structures may contain allosteric sites.

The catalytic site and binding site together form the enzyme's 'active site,' and the remaining structure of the enzyme serves to maintain the precise orientation and dynamics of the enzyme.

Enzymes are usually much larger than the substrate. 

 

Mode of action

 Enzymes are the catalyst and show the following properties :

1. Enzymes increase the reaction rate by lowering the activation energy.

2. Enzymes are not consumed in the reactions.

3. Enzymes do not alter the equilibrium of the reaction.

4. Enzymes do not participate in the chemical reaction.

5. Enzymes are very specific.

Specificity is achieved by

Ø binding pockets

Ø complementary shape,

Ø charges of the substrate, and

Ø the hydrophilic or hydrophobic character of the substrate. 

Some enzymes are particular for the 'Proofreading' mechanism, while some enzymes display 'enzyme promiscuity' act on a wide range of different physiological substrates.

 Two hypotheses are there to explain the specificity of enzymes

Ø  lock and key model and

Ø induced fit model -this is widely accepted. 

 The unique three-dimensional structure of the enzyme is responsible for its specific binding property.

Enzyme activity can be affected by

Ø JAn activator is a molecule that increases the activity of the enzyme.

Ø  L Inhibitors are molecules that decrease the activity of the enzyme.

Conditions for optimal functioning of enzymes

 Enzymes function properly in optimal conditions.

 

J The optimal temperature usually is 37⁰ centigrade for many enzymes. Enzymes are permanently damaged when exposed to excessive heat and lose their catalytic property.

 J Optimal pH is essential for their proper action. Some enzymes are active in acidic media and become inactive in alkaline media and vice

versa.

J Proper concentration of the substrate.

Commercial use of enzymes

Ø In antibiotic synthesis

Ø In the food industry

Ø  Enzymes are manufactured for medical treatments.

 

Classification

Classification of the enzyme is based on:

1.    Amino acid sequence and

  2. Enzymatic activity

 The name of an enzyme is usually given from

The substrate on which it acts, for example, lactase enzymes working enzymeson lactose, and

The name of the chemical reaction it catalyzes, for example, transferase.

Suffix' ase' is added to the name of the substrate or the reaction.

 The International Union of Biochemistry and Molecular Biology recommended number the 'enzyme Commission' to recognize the enzymes.

Ø EC 1 -→  oxidoreductase -oxidation-reduction reactions,

Ø EC 2 →    transferases  -transfers functional group

Ø EC 3 →    hydrolases     - causing hydrolysis

Ø EC 4 →    Cleavases –cleaves bonds other than hydrolysis and oxidation

Ø EC 5 → isomerases – isomerization

Ø EC 6 → linkages- join two molecules by covalent bond and

Ø EC 7 → translocation -the movement of Ions and molecules.

The groups are further subdivided by the nature of the substrate, product, or chemical reaction.

Simple enzymes do not need any cofactor for their action, e.g., pepsin.

  Enzymes are very specific, but different enzymes catalyze the same chemical reaction called 'isoenzyme.'

Apoenzyme or apoprotein is the protein part of an enzyme and can attach to its specific substrate. But remains inactive without cofactor. When it binds with its cofactor, it becomes enzymatically active and is known as the holoenzyme. It is essential for an enzyme's enzymatic activity and specificity to its substrates.

Holoenzyme  is apoenzyme plus cofactor.

Coenzymes are non-protein organic complexes.

Cofactor essential for apoenzyme may be

J metal ion Mg²⁺ , Fe³⁺

J organic molecule called coenzyme NAD⁺, NADP⁺.

The prosthetic group is the cofactor tightly bound to an apoenzyme, known as a prosthetic group. 

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https://learn-and-fly.co.in/differences-between-hormones-and-enzymes.  

Hashtag: Enzymes # Apoenzyme #  Holoenzyme# Globular proteins#  

 Cofactor # Prosthetic#  Catalytic #  isoenzyme#

Internal link: https://blog.totalphysiology.com/2022/02/what-is-hormone-endocrinology-types.html

 

https://blog.totalphysiology.com/2021/05/digestion-and-absorption-of.htm

 

https://blog.totalphysiology.com/2021/03/2021-google-ductlessglands-we-must-know.html

https://learn-and-fly.co.in/differences-between-hormones-and-enzymes.  differences between hormones and enzymes

 

External link:https:// en.m.wikipedia.org>enzyme.