Enzyme Catalysis



Uses of enzymes

Following are the applications of enzymes:
  • Production of alcohols from cellulose
  • Improve phosphate utilization
  • Used in photography processes


Action of enzymes

The mechanism by which enzymes catalyse chemical reactions begins with the binding of the substrates to the active site on the enzyme. 



Enzymes are biological catalysts. Catalysts are substances that increase the rate of chemical reactions without being used up. Enzymes are also proteins that are folded into complex shapes that allow smaller molecules to fit into them. The place where these substrate molecules fit is called the active site.Examples are lactase, alcohol dehydrogenase and DNA polymerase.


Characterisitcs of enzyme

  • Enzymes possess great catalytic power. 
  • Enzymes are highly specific.
  • Enzymes show varying degree of specificities.
  • Absolute specificity where the enzymes react specifically with only one substrate. 
  • Stereo specificity is where the enzymes can detect the different optical isomers and react to only one type of isomer. 
  • Reaction specific enzymes, these enzymes as the name suggests reacts to specific reactions only.


Specificity and efficiency of enzymes

Specificity: Each enzyme catalyses only one chemical reaction.
Efficiency: They are very efficient catalysts. They speed up the rate of reaction by factors of upto


High efficeieny of a small quantity of enzymes

The reason is that enzymes are also generated after their catalytic activity but their rate of regeneration is very fast, of the order of 1 million times per minute.


Optimum temperature and pH of enzyme

Enzyme catalysed reactions have maximum rate at physiological pH of around 7.4 and human body temperature of under one atm pressure.


Mechanism of enzyme catalysis

mechanism of enzyme catalysis proceed in two steps:
Step 1: Binding of substrate to enzyme to form activated complex.
Step 2: Decompostion of the activated complex to form product.


Intermediate compound formation theory

According to this theory, the desired reaction is brought about by a path involving the formation of an unstable intermediate compound, followed by its decomposition into the desired end products with the regeneration of the catalyst. (a) When the intermediate compound is reactive and reacts with the other reactants.


Active centres

On a molecular level, most catalysts (or most substances really) are not just flat surfaces, they have complex three-dimensional shapes. The substrate often has to bind to the catalyst in a very specific way in order for the catalysed reaction to take place - this is the active centre.