Enzymes And Hormones


ENZYMES are the biological catalyst that increases the rate of biochemical reactions without any changes.

An organic, protein-based catalyst that is not itself used up in the reaction. It is naturally produced by living cells to catalyze biochemical reactions. Each enzyme is highly specific with regard to the type of chemical reaction that it catalyzes, and to the substances (called substrates) upon which it acts. This specific catalytic activity and its control by other biochemical constituents are of primary importance in the physiological functions of all organisms. Although all enzymes are proteins, they may, and usually do, contain additional nonprotein components called coenzymes that are essential for catalytic activity.

Apoenzyme: The protein portion of a holoenzyme. Many (but not all) enzymes are composed of functional “pieces” (i.e., a protein piece (chain) and another piece that is an organic and/or inorganic molecule). The other piece is known as a cofactor, and it may be removed from the enzyme under certain conditions, after which the resulting inactive enzyme is known as an apoenzyme. The inactive apoenzyme becomes functionally active again if it is allowed to recombine with its cofactor.

Holoenzyme: The entire, functionally complete enzyme. The term is used to designate an enzyme that requires a coenzyme in order for it to function (possess catalytic abilities). The holoenzyme consists of the protein part (apoenzyme) plus a dialyzable, nonprotein coenzyme part that is bound to the apoenzyme protein.

Coenzyme: A nonproteinaceous organic molecule required for the action of certain enzymes. The coenzyme contains as part of its structure one of the vitamins. This is why vitamins are so critically important to living organisms. Sometimes the same coenzyme is required by different enzymes involved in the catalysis of different reactions. By analogy, a coenzyme is like a part of a car, such as a tire, which can be identified in and of itself and which can, furthermore, be removed from the car. The car (enzyme), however, must of necessity have the tire in order to carry out its prescribed function.
Coenzymes have been classified into two large groups: fat soluble and water soluble.
Examples of a few water-soluble vitamins are thiamin, biotin, folic acid, vitamin C, and vitamin B12. Examples of fat-soluble vitamins are: vitamins A, D, E, and K.

Coenzyme A: A water-soluble vitamin is known as pantothenic acid. A coenzyme in all living cells is required by certain condensing enzymes and functions in acyl-group transfer and in fatty acid metabolism.

Cofactor: The term cofactor is a general term. A nonprotein component is required by some enzymes for activity. The cofactor may be a metal ion or an organic molecule called a coenzyme.  Cofactors are generally heat stable.


Enzymes are produced in exocrine glands.Hormones are produced in endocrine glands.
They perform their action on the site/place where they are produced.Hormones perform their action two different places -1-from where they are produced and
-2-they are carried by the blood.
All enzymes are protein (except-ribozyme)They are derivative of proteins, amino acids, and steroids,polypeptides,terpenoids, phenolic compounds or amines.
Enzymes perform in particular temperature, and on pH level.No effect of pH level or temperature, but sometimes effected by external factors also.
Enzymes are the catalyst, almost it enhances the biochemical reactions.Hormones are the chemical messenger that provide signals to the cell for performing the particular function.
Molecular weight: HigherMolecular weight: Lower
Enzymes act at the place where they are formed/produced.Hormones are carried by the blood to different part of the body for giving signals to the cell.
Enzymes depend on Hormones. Enzymes start reacting only when it get the message from hormone.Hormones do not depend on an enzyme.
Enzymes are substrate specific i.e. depends on the substrate to perform the function.Hormones are target cell specific and depend on positive and negative feedback mechanism.
Enzymes are non-diffusable through a cell membrane.Hormones are diffusable through the cell membrane.
Enzymes take part in metabolism.Hormones regulate the metabolic activity i.e. while giving signals to the cell for performing various body functions.
Enzymes have no effect of age.Hormonal changes can be seen with age like menopause, puberty.
Comparatively fewer chances of occurrence of diseasesHormonal disorders are very common, and even a single wrong message sent to the cell may give rise to life-long disease or disorders.
Enzymes can be reutilized after their function as they are the catalyst and remain unchanged.Hormones cannot be reutilized once their function is over, they naturally get destroyed.
Examples: Oxidoreductase,
Hydrolase etc.
Examples: Insulin,
Thyroid (T3, T4).
Enzymes act as biological catalysts.As Hormones are not act as catalysts.