Key difference - hormone vs. enzyme
Hormones and enzymes are two substances produced by plants and animals that help regulate various functions in the body. Hormones can either be proteins or steroids. Enzymes are mainly proteins. Both hormones and enzymes are released by glands in animals. Hormones are chemicals, but enzymes are biological catalysts. The main difference between hormone and enzyme is that the hormone transmits messages to other parts of the body and triggers a specific cellular response in target tissues and organs, while enzyme is a biological catalyst that increases the speed of a specific biochemical reaction without alteration.
1. What is hormone - definition, properties, functions, examples 2. What is enzyme - definition, properties, functions, examples 3. What is the difference between hormone and enzyme?
What is a hormone
A hormone is a product of living cells that circulates in fluids such as blood or juice and has a specific, usually stimulating effect on the activity of cells far away from their place of origin. Synthetic substances can also react as hormones. So hormones are chemical messengers that help one part of the body to communicate with the other part of the body by sending signals. In animals, they are released directly into the bloodstream by endocrine glands and circulate through the body until the target tissue or organ is found. Some of the endocrine glands in the body and their hormones are listed in Table 1.
Table 1: Endocrine glands and their hormones
Growth hormone (GH), prolactin, follicle stimulating hormone (FSH) and luteinizing hormone (LH)
Insulin, glucagon and amylin
Insulin-like growth factor 1 (IGF-1)
Thyroxine and calcitonin
Aldosterone and cortisol
Estrogen and progesterone
The first contact of a hormone with a particular cell or tissue can trigger important reactions, such as function. Different types of hormones are released by the body with different biological functions. Hormones can be polypeptides, amines, terpenoids, steroids or phenolic compounds. Because hormones are extremely powerful molecules, some hormones can have a huge impact on the body. Hormones are destroyed according to their effects. Therefore, they cannot be reused. Figure 1 shows different classes of hormones.
Hormonal imbalances can occur due to age, illness, genetic disorders, exposure to environmental toxins, and disorders of the body's natural rhythm. Overproduction of hormones as well as underproduction of hormones cause health problems. If there is a hormone deficiency, synthetic hormone replacement therapy can be used.
What is an enzyme?
An enzyme is a protein molecule that acts as a biological catalyst and regulates the speed of the biochemical reaction. It does not change its structure during the action; therefore it is reusable. All aspects of metabolism in cells are catalyzed by enzymes. Large nutrient molecules like carbohydrates, proteins and lipids are broken down into small molecules, which converts chemical energy into other cellular processes like the formation of macromolecules, starting from their precursor molecule. All enzymes except ribozymes are proteins. The amino acid sequence of the polypeptide chain determines the structure of the protein, which is essential for its effect. The structure of the protein varies with temperature or pH. Once denatured, enzymes irreversibly lose their ability to catalyze reactions. Due to the action of an enzyme, additional chemical components such as cofactors are required. These cofactors can either be coenzymes such as vitamins or prosthetic groups such as metal ions. An enzyme with its active center is shown in Figure 2 .
Since enzymes can be used over and over, only a small amount of enzyme is required to catalyze a reaction. The action of enzymes can be regulated mainly through allosteric control. Hereditary human diseases such as phenylketonuria and albinism are caused by a lack of an enzyme.
Enzymes also have industrial uses such as fermenting wine, leavening bread, brewing beer and curdling cheese. In medicine, enzymes are used to diagnose diseases, promote wound healing and kill pathogenic microorganisms.
Difference Between Hormone and Enzyme
Hormone: Hormone is a regulatory substance that is produced in an organism and transported in tissue fluids such as blood or juice and stimulates certain cells or tissues to act.
Enzyme: Enzyme is a substance produced by an organism that can catalyze a specific biochemical reaction.
For plants and animals:
Hormone: Hormones are polypeptides, amines, terpenoids, steroids or phenolic compounds.
Enzyme: Enzymes are proteins that can contain metallic groups. The exception is ribozymes, which are RNA with catalytic activity.
Hormone: Hormones do not have prosthetic groups.
Enzyme: Enzymes contain coenzymes and cofactors as prosthetic groups.
Hormone: Hormones have a low molecular weight.
Enzyme: Enzymes have a comparatively high molecular weight.
Diffusion across the cell membrane
Hormone: Hormones can be diffused through the cell membrane.
Enzyme: Enzymes cannot be diffused through the cell membrane.
Hormone: Hormones are signals that are transmitted between cells or organs.
Enzyme: Enzymes catalyze chemical reactions by increasing the speed of the reaction.
Hormone: hormones are damaged during the process; therefore they cannot be reused.
Enzyme: Enzymes do not change according to their function.
Hormone: Hormones are regulated by the brain or external factors.
Enzyme: Enzymes are regulated by allosteric control, isoenzymes, covalent modification, proteolytic activation and protein turnover.
Influence of temperature and pH
Hormone: Hormones are not affected by temperature and pH.
Enzyme: Enzymes are influenced by temperature and pH.
Hormone: Hormones have various functions in regulating growth, development and reproduction.
Enzyme: Enzymes have unique but essential functions in the body.
Hormone: Oxytocin, cortisol, testosterone and estrogen in animals and abscisic acid, cytokines and gibberellins in plants are examples of hormones.
Enzyme: hydrolases, oxidases and isomerase are the examples of enzymes.
Hormone: Hormones are produced and secreted by the endocrine glands.
Enzyme: Enzymes are produced and secreted by exocrine glands.
Hormone: Hormones are transported to the site of action via the blood.
Enzyme: Enzymes work either at the point of origin or in a nearby organ.
Type of function
Hormone: The function of hormones depends on positive and negative feedback reactions.
Enzyme: The function of enzymes depends on the presence of substrate.
Hormone: Excessive or decreased levels of hormones cause disease.
Enzyme: Enzymes cause diseases through deficiency.
Hormone: Hormones transmit signals to enzymes.
Enzyme: Enzymes work depending on the signals from hormones.
Variation with age
Hormone: Hormones tend to change with age.
Enzyme: Enzymes do not change with age.
Hormones and enzymes are two substances that are produced in plants and animals and that can catalyze chemical reactions. Hormones are small chemicals that have a different site of action than where they were created. They are produced and secreted by endocrine glands and circulate in fluids such as blood or juice and carry chemical signals around the body. Therefore, different tissues and organs communicate through hormones. Enzymes are protein molecules that catalyze biochemical reactions in the body. They are produced on site. Enzymes tend to change their structure under unfavorable temperature and pH conditions. However, the main difference between hormone and enzyme lies in how they work in the body.
Reference: 1. Wiley, F. "What are hormones?" EverydayHealth.com. Np, Oct. 19, 2015. Web. May 29, 2017. <http://www.everydayhealth.com/hormones/guide/> .2. Mandal, A. "What are hormones?" News-Medical.net. Np, Dec 02, 2013. Web. May 29, 2017. <http://www.news-medical.net/health/What-are-Hormones.aspx> .3. "Enzyme." Encyclopædia Britannica. Encyclopædia Britannica, Inc., nd Web. May 29, 2017. <https://www. britica.com/science/enzyme>.
Image courtesy: 1. "1802 Examples of the Structure of Amine Peptide Proteins and Steroid Hormones" from OpenStax College - Anatomy & Physiology, Connexions website. June 19, 2013 (CC BY 3.0) via Commons Wikimedia 2. “Phenylalanine hydroxylase mutations” By Thomas Shafee - Own work (CC BY 4.0) via Commons Wikimedia