Enzymes 26/10/2016

Enzymes - Enzymes are Biological catalysts. They are found in all living cells which speed up chemical reactions in our cells/body.
Without Enzymes, chemical reactions inside our cells/body will work far too slowly for life to exist. The Enzyme Activity is affected by both temperature and the pH level.

Catalysts - Catalysts are chemicals that speed up the rate of a chemical reaction. The catalyst remain unchanged and are not used up in the reaction.

The effect of catalase on Hydrogen Peroxide

Catalase is an enzyme. It is found in most living cells. It breaks down hydrogen peroxide (H2O2) into water plus oxygen.
catalase
An equation for this is: Hydrogen peroxide -------------> Water + Oxygen (H2O2 Catalase H20 + O2)
Enzyme
The Enzymes act on a substrate to produce a product. The general word equation for an enzyme controlled reaction is: substrate -------------> product

Enzyme Specificity

One Enzyme is specific to one substrate - One enzyme can only Catalyse one reaction, eg Catalase WILL ONLY break down hydrogen peroxide to water and oxygen. An enzyme and its substrate fit together like a lock and a key. The enzyme 'unlocks' the substrate to give a new product.

Substrate - The Substrate is the substance upon which the enzyme acts resulting in the formation of an object. It joins to the active site.

Product - The product is the molecule present at the end of the chemical reaction.

Since an enzyme only acts on one specific substrate, each enzyme is said to be specific.

Breakdown and buildup reactions

Enzymes are part of two types of reactions: Breakdown and buildup reactions. A breakdown reaction is a large substrate broken down into smaller product(s). A buildup reaction is a small substrate built up into a larger product. An example of a breakdown reaction is: Amylase, which is present in saliva that BREAKS DOWN starch into maltose (a sugar). The equation for this is:
Amylase
Starch -------------> Maltose

A buildup reaction may also be called as a Synthesis Reaction. An example of this is: Phosphorylase, which is present in plants that builds glucose-1-phosphate up into Starch. The equation for this is:
glucose-1-phosphate
Phosphorylase --------------------------------> Starch

Enzyme Reactions:

Breakdown reactions:
Amylase
Starch --------------> Maltose
Catalase
Hydrogen peroxide -------------> water + oxygen
Lipase
Fats ------------> Fatty acids + Glycerol

Synthesis/Breakdown Reaction:
Phosphorylase
Glucose-1-Phosphate ----------------------> Starch

Enzymes and Temperature

Enzymes made of protein. All proteins are affected by temperature. Enzymes work slowly at low temperatures, but it does not do any damage to the enzyme. As the temperature increases the enzyme will work faster till a certain point. At high temperatures such as 50c, enzymes are destroyed and no longer work at all. The shape of the enzyme is permanently changed by the high temperature, so the substrate and enzyme don't fit together anymore.

Effect of pH on Enzymes

pH is a measure of how acidic or alkaline a substance is.

pH of less than 7 = Acidic
pH of exactly 7 = Neutral
pH of more than 7 = Alkaline

Enzymes are also affected by the pH, just like the temperature. Enzymes will only work within a narrow range of the pH scale. The pH they work at depends on where they work in the body. For example, amylase works best at pH 7 - it is present in saliva, pepsin is an enzyme found in stomach acid - it works best at pH 2.

Optimal Conditions

Optimal means 'best'. Optimum Conditions simple mean the conditions that enzymes work best at. Example of this is; Human enzymes work best at 37c - this is their optimal temperature. The optimal pH of different enzymes changes depending on where in the body it is active - e.g amylase (mouth) has an optimal pH of 7, whereas pepsin (Stomach) has an optimal pH of 2.

Enzymes and Biotechnology

In addition to being essential for life, enzymes are also used in a number of biotechnology industries. Examples include:

-Using enzymes in biological washing powders.

-Using enzymes in food modifications eg turning cloudy apple juice into clear apple juice.

	Created by Reece Thompson about 8 years ago

Information about Enzymes, reactions and more.