Hydrogen Peroxide/Blood

and

The Function of Catalase in

Humans

Jim Goetz

Hydrogen peroxide is composed of two atoms of hydrogen and two atoms of oxygen. It is

simple to obtain and most humans have used it topically at one point in their lives to

clean, rinse and/ or disinfect

Most people purchase hydrogen peroxide in a 3% solution. This means the bottle contains

97-percent water and 3-percent hydrogen peroxide. One can also obtain 97% solution,

which is often used in pools or hot tubs. However anything over 3% can cause burns and

should not be touched with bare skin.

When one applies hydrogen peroxide to an open wound it foams. This is because blood

and cells contain an enzyme called catalase. Since an abrasion contains both blood and

damaged cells, catalase is plentiful.

When the catalase comes in contact with hydrogen peroxide, it breaks down the hydrogen

peroxide into water and oxygen gas.

2H202 –(catalase) 2H20 + 02

Catalase breaks down hydrogen peroxide with millions of reactions per second. The

bubbles one may see in the foam are pure oxygen bubbles being created by the reaction

of catalase and hydrogen peroxide.

Hydrogen peroxide does not foam in the bottle or on your skin because there is no

catalase to help the reaction to occur. Hydrogen peroxide is stable at room temperature.

Catalase is a tetramer (protein with four subunits) of four polypeptide chains. Each chain

has over 500 amino acids in length. It contains four polyphorin ring groups that allow it

to react with the hydrogen peroxide.

Catalase has an optimum pH (in humans) of around 7 (neutral). The optimal temperature

(in humans) is 37 degrees C. While all human organs produce catalase, the largest

quantities can be found in the liver.

While there are theories, the complete mechanism of catalase is apparently unknown.

Hydrogen peroxide is a harmful by-product of many normal metabolic processes in the

human body. In order to prevent damage of cells and tissues, hydrogen peroxide must be

quickly converted into a less dangerous form.

In humans, catalase is located in the cellular organelle called peroxisomes.

Catalase is used by cells to rapidly catalyze the decomposition of hydrogen peroxide into

inert substances such as unreactive gases, oxygen and water.

Hydrogen peroxide is used as a potent antimicrobial agent when cells are infected with a

pathogen. Pathogens that are catalase-positive include: mycobacterium tuberculosis,

Legionells pneumophila, and Campylobacter jenuni. These pathogens synthesize catalase

with the purpose of deactivating peroxide radicals, which allows them to survive

unharmed within the host.

References

Chelikani P, Fita I, Loewen PC (January 2004). "Diversity of structures and properties among catalases". Cell. Mol. Life Sci. 61 (2): 192–208

Goodsell DS (2004-09-01). "Catalase". Molecule of the Month. RCSB Protein Data Bank. Retrieved 2007-02-11

Alberts B, Johnson A, Lewis J, Raff M, Roberts K, Walter P (2002). "Peroxisomes". Molecular Biology of the Cell (4th ed.). New York: Garland Science