Properties of Enzymes

Enzymes possess the following major properties :

They are biocatalysts.

Most of the enzymes are globular proteins. Being proteins, they are coded for by DNA.

All components of cell including cell wall and cell membrane have enzymes. Maximum enzymes (about 70%) are found in mitochondria.

Every cell produces its own enzymes. Have high mol. wt.e.g. - bacterial ferrodoxin - 6000, catalase-25000 urease-483000, pyruvate dehydrogenase-4600,000

Their presence does not alter the nature or properties of the end product(s) of the reaction.

They are very efficient, as a very small amount of catalyst brings about the change of a large amount of substrate. For example, one molecule of the enzyme catalase can catalyse the decomposition of about 600

thousand molecules per second of hydrogen peroxide to water and oxygen at body temperature. Without a catalyst at all, reaction rates would be millions of times slower.

They are highly specific, that is an enzyme will generally catalyse only a single reaction. Catalase, for example, will only catalyse the decomposition of hydrogen peroxide.

The catalysed reaction is reversible.

Their activity is affected by pH, temperature, substrate concentration and enzyme concentration.

Enzymes lower the activation energy of the reactions they catalyse.

Enzymes possess active sites having specific shapes. where the reaction takes place.

Enzymes functional outside the living cells are called exoenzymes. e.g. enzymes present in digestive juices, lysozyme of tears.

Enzymes functional inside the living cells are known as endoenzymes e.g. Enzymes of Kreb’s cycle (inside mitochondria), Enzymes of glycolysis (inside cytoplasm).