Enzymes / biocatalysts – Simplified meaning, classes and characteristics

Most  reactions in living organisms cannot proceed spontaneously like those of inorganic chemistry.   Hence they need a medium or mechanism of piloting their reactions. Left alone,  it may take a single reaction process up-to 20 years to give the product.  So, enzymes are present in Biological systems to induce the rate of reaction.

Enzyme / Biocatalysts confirmation
Example of an enzyme

Definition :

Enzyme are globular proteins(exept RNA enzymes) which alter the rate of biological reactions.

General hints:

There are certain important hints to note

* Enzymes are mostly proteins (globular)

* They affect the rate of reaction

* They are biological catalysts

* The can  either increase ( positive enzyme)  or decrease ( negative enzyme)  the rate of biological reactions.

Examples : 1. Hexokinase 2. Phosphatase  3. Phosphorylase  4. RUBISCO( ribulose-1,5-bisphospo carboxylase oxygenase  found in Calvin Benson cycle —photosynthesis

Classification of enzymes:

Enzymes can be classified into seven groups based on the reactions they catalyze. There is an addition of translocase to the previous six classes, making them seven. They follow a standard serial.

They can be easily recalled using this simple antonym… OTHLILT.  They are






Naming of enzymes:

They are named in two ways

1. Trivial normencleture

2. IUB normencleture

         Trivial normencleture uses the type of reaction or the product formed by the enzymic reaction.  Examples includes  1. Phosphatase  2. Phosphorylase 3. Enolase 4. Ribulose-1,5-bispopho carboxylase oxygenase in photosynthesis. Etc

IUB uses numbers to indicate the class of enzyme,  type of enzyme, product type formed etc. 


1. They are powerful : enzymes are capable of reducing the supposed time of reaction in a million folds. It can take a millisecond instead of years. 

2. They are highly specific : enzymes have a particular substrate they act upon to give a product.  The degree of specificity differs greatly. Some are stereo specific, group specific etc , except papain which is used as a meat tenderizer 

3. They are proteins: all enzymes are proteins. Not just all proteins, they are long chain globular proteins. They have achieved their tertiary and quatenary structures which enables them to have active sites and possibly, regulatory site.

Factors that affect Enzyme activity

1. Temperature

Enzymes can be easily denatured by heat.  An increase or decrease in temperature will definitely affect it’s activity. They work at optimum temperature. Some can withstand high temperature such as biocatalysts extracted from Thermos aquaticus, as used in PCR.

2. pH

Acidity and alkalinity also affects biocatalystic  activities. Hence they work best at optimum pH. Body biocatalysts will tend to work best at the pH of the region of the body it’s found. Enzymes of the pancreas will tend to withstand high acidity.

3. Presence of an inhibitor.

Inhibitors compete with the substrate of the biocatalysts, or attacks the ES complex. large concentration of inhibitors will halt the catalytic activity of a biocatalysts.

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