What are the differences between hormones and enzymes?

Basis of differentiation 

Hormones 

Enzymes

Definition 

Are regulatory substances that are produced in one part of an organism and transported through tissue fluids, triggering specific cellular reactions in target tissues and organs in other parts of the organism

Are biological catalysts that bring about biological reactions without undergoing any changes in their composition or structure

Mode of action 

Act as messengers that stimulate various functions in the body

Act as catalysts that speed up the rate of a reaction

Production site

Produced by endocrine glands such as thyroid and pituitary glands

Produced by exocrine glands such as gastric glands and salivary glands

Effect of age on production

Production is affected by age such as in puberty

Production is not affected by age

Sites of production and action

The site of action is different from the production site

The site of action is the same as the production site

Functions 

Have diverse functions related to regulating growth, development, and reproduction

Have unique but essential functions in the body

Molecular weight

Have low molecular weight

Have relatively higher molecular weight

Chemical composition

May be composed of proteins, amino acids or steroids

Predominantly composed of proteins

Chemical stability

Chemical composition changes during the process so they cannot be reused in most cases

Chemical composition remains the same during the process so they can be reused 

Regulation 

Are regulated by the brain or external factors

Are regulated by allosteric control, protein turnover, covalent modification, proteolytic activation, and isoenzymes

Effect of temperature and pH 

Not affected by temperature, pH, or other external factors

Significantly affected by temperature, pH levels, and other external factors

Diffusion through cell membrane

Can diffuse through the cell membrane

Cannot diffuse through the cell membrane

Examples

- Insulin 

- Melatonin 

- Cortisol

- Estrogen 

- Oxidases

- Hydrolases

- Isomerases