IMMOBILIZED ENZYMES FOR INDUSTRIAL APPLICATIONS

CHAPTER ONE

1. 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.

• Oxidoreductases: these catalyze the transfer of hydrogen or oxygen atoms or electrons and are using NAD⁺/NADP⁺ as an electron acceptor.
• Transferases: catalyze the specific grouping transferring e.g. Methyl, Carbonyl and COA.
• Hydrolyses: catalyze transfer of hydrolytic reactions e.g carbonsilic ester, thiolester, endoribonuclear and dipeptile hydrolyses.
• Liases: these are enzymes that catalyze cleaving of bones by reaction.
• Isomerizes: these catalyze intra molecular rearrangements.
• 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.

 Denaturation      Increase reaction rate

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 in charge 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.