The Effect of Enzyme Concentration on the Rate of an Enzymic Controlled Reaction

The Effect of Enzyme Concentration on the Rate of an Enzymic Controlled Reaction

Enzymes are protein molecules, which can be defined as Biological

catalysts, which alter the rate of a reaction without the enzymes

undergoing change themselves. Enzymes are usually specific to one

singular reaction.

Enzymes are globular proteins with the helix coiled into a precise

three-dimensional tertiary structure, with Hydrophilic R groups held

by four different types of bonds:

1. Hydrogen

2. Disulphide

3. Ionic

4. Hydrophilic / Hydrophobic

Enzymes possess an active site, a region, usually a cleft or

depression to which another molecule can bind. This specific molecule

is the enzymes' substrate. The precise shape of the active site allows

the substrate to bind perfectly to the active site. This is known as

the 'Lock and Key system'. The combined structure is defined as the

Enzyme-Substrate Complex.

As the Enzyme-Substrate Complex forms, interaction between the R

groups of the enzyme and the atoms of the substrate can break, or

encourage the formation of bonds in the substrate molecule, forming

one or multiple products.

Enzymes operate by reducing activation energy. In terms of the

Enzyme-Substrate Complex, this is done through lacing strain upon the

original bonds, through the enzyme and substrate molecules binding

together, and the way in which the substrate is held allows the

molecules to react more easily. In turn, this is lowering the

activation energy, allowing the reaction to proceed faster.

The course of an enzymic controlled reaction is quite simplistic in

theory. The rate of such a reaction is always fastest at the

beginning. This short period is called the initial rate of reaction,

and lasts for approximately 30 seconds.

When investigating the effect of enzyme concentration it is fairest to

look at initial rate of reaction, as once the reaction is underway,

the amount of substrate available in the reaction begins to vary, as

substrate is converted to products at different rates, all depending

upon concentration.