IMMOBILIZED ENZYMES FOR INDUSTRIAL APPLICATIONS

CHAPTER ONE

CHAPTER ONE

CHAPTER ONE

1.0 CHAPTER ONE

INTRODUCTION

The history
of enzymes may be regarded as commencing with the work of Dubrunfaut, (1830)
who prepared malt extract from germinating barley seeds.  This extract possessed the power of
converting starch into sugar.  Therefore,
it is imperative to briefly discuss the general facts and concepts of Enzymes
before passing to detailed study of the various applications of immobilized
enzymes in industries.

1.1   Enzymes: These can be defined as the
substances which catalyzing or alter the rate of chemical reactions. All enzymes
      are conjugated proteins and usually
associated with non – proteins groups. 
The catalytic activities depend on the maintenances of their native
structure and slight variations may result in significant changes in their
activities.  A common feature of all
enzymes in the presence of a cleft / depression in the structure which is line
mainly with hydrophobic amino acids into which the substrate fixed which is
known as the ‘Active site’.  Certain
amino acids residues which are concern with either orientation of the
concentrate and the ends with the specificity of the enzymes or are involved in
the catalyst of the reaction are located in this cleft, those amino acid that
are associated with the latter role form the active site of the enzymes and are
often located towards its base of this cleft, those amino acid that are
associated with the latter role form the active site of the enzyme and are
often located towards its base of this cleft. 
In most cases, they are ionic or reactive and they include instidine,
serine as well as Glutaric and Asphatic acid. 
In addition, the Ions from a solution particularly cations may aid
either location of substrate of the reaction. (Extracted from fundamentals of
the biochemistry  6^th Ed. S.
ched & Co Ltd. New Delhi. Pg. 334 -348)  

1.2  CLASSIFICATION
OF ENZYMES

        Enzymes
can be classified according to their catalytic actions on various compounds.

ü  
Oxidoreductases: these catalyze the transfer of
hydrogen or oxygen atoms or electrons and are using NAD⁺/NADP⁺
as an electron acceptor.

ü  
Transferases: catalyze the specific grouping transferring e.g. Methyl, Carbonyl
and COA.

ü  
Hydrolyses: catalyze transfer of hydrolytic reactions e.g carbonsilic
ester, thiolester, endoribonuclear and dipeptile hydrolyses.

ü  
Liases: these are enzymes that catalyze cleaving of bones by
reaction.

ü  
Isomerizes: these catalyze intra molecular rearrangements.

ü  
Ligases: catalyses formation of bones and required ATP.

1.3  FACTORS AFFECTING
ENZYMES ACTIVITIES

1.     TEMPERATURE: An increase in temperature
of an enzymes increase the rate of all chemical reactions include those
catalyze by the enzymes, it also increases the rate of denaturation of enzymes
proteins, denaturation occur more readily.

      Effect                                A

         B

                                        Optimum
temperature

                       Overall

                      
Effect

Table 1.31                Temp.                                         (o^o)

EFFECT OF TEMPERATURE ON ENZYMES

Because of denaturation of A, the proportion of active fall
and these two processes result in deducted line.

2.     PH: All enzymes are sensitive to
changes in P.H and function best over a very limited range with a definite P.H
optimum. The effects of P.H are to the changes in the tonic state of both amino
acid residues of the enzymes and substrate molecules.

There alterations incharge will affect
substrate bonding and the resulting rate of the reaction over a narrow P.H
range, this effect will be reversible but extreme acidity or alkalinity often
cause serious distortion of protein structure and result in permanent
denaturation.