Aptamers: DNA, Peptides & Affirmer

Instructor: Brittany W.

Brittany has a bachelor's degree in biological sciences and biochemistry.

Learn about aptamers and the compounds that comprise them. Discover how they function, what purposes they serve in the biomedical sciences industry, and how they differ in form and function. Updated: 04/15/2022

Aptamer Overview

Nucleic acids are a molecular category that mainly consists of deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). Aptamers are relatively small nucleic acid molecules that bind specific target molecules that include:

  • Proteins
  • Peptides
  • Carbohydrates
  • Toxins
  • Other small molecules
  • Live cells

Aptamers are highly selective and specific, meaning a certain kind of aptamer will only bind to a target molecule. Aptamer specificity depends on its three-dimensional conformation, also known as a tertiary structure, or the overall shape a molecule makes. In most cases, the tertiary structure of a molecule also relates to its function. For aptamers, the general form of their molecular structure allows them to bind or select target molecules. The aptamer and its target must physically and chemically fit together for selection to occur.

Nucleic acid aptamers are DNA and RNA molecules comprised of individual nucleotides.
molecular structure of RNA aptamer

Aptamer Functionality

The high selectivity and specificity of aptamers appear in a variety of functions:

  • Laboratory research
  • Food and environmental safety
  • Clinical therapeutics and diagnostics
  • Pathogen recognition
  • Cancer recognition
  • Stem cell marking

Pathogens are disease-causing agents such as bacteria, viruses, and fungi. Aptamers can be used for target-specific therapy to treat some forms of cancer and chronic conditions such as ulcerative colitis and Crohn's disease. They have even been used to halt the replication of HIV. When scientists select a specific cell marker, receptor, or identifying protein, they can target and inhibit the key factors that encourage pathogenic agents to replicate and take over the body.

DNA Aptamers and Binding Peptides

DNA aptamers are short-chain molecules of approximately 20 to 100 nucleotides long. Nucleotides are the building blocks of DNA and RNA; hence, the molecules that result are nucleic acids.

Binding peptides are among the most common molecules that bind to an aptamer. Peptides are short-chain protein molecules made up of a string of amino acids - the building blocks of proteins. When an aptamer binds to a peptide or protein, it:

  • Inhibits protein-protein interactions that could stop the progression of a disease
  • Inhibits a receptor that halts a harmful, biochemical cascade
  • Marks an abnormal cell for destruction by binding to a protein on the cell surface

Affirmer Aptamers

Affirmers are peptide aptamers. In other words, affirmers are proteins that bind to other proteins and various molecules. Therefore, affirmers can bind to similar binding peptides as nucleic acid aptamers. However, one peptide (the affirmer) selects for the other.

To unlock this lesson you must be a Study.com Member.
Create your account

Register to view this lesson

Are you a student or a teacher?

Unlock Your Education

See for yourself why 30 million people use Study.com

Become a Study.com member and start learning now.
Become a Member  Back
What teachers are saying about Study.com
Try it now
Create an account to start this course today
Used by over 30 million students worldwide
Create an account