From the Guidelines
The order of peptides by molecular size from smallest to largest is dipeptides, tripeptides, oligopeptides, and polypeptides, with sizes ranging from 2 amino acids to hundreds or thousands of amino acid residues. The smallest peptides, dipeptides, consist of just two amino acids linked by a peptide bond 1. Tripeptides contain three amino acids joined together, and oligopeptides typically contain between 3 and 10 amino acids, though some definitions extend this range to 20 amino acids. Polypeptides are the largest, containing more than 10-20 amino acids and can reach lengths of hundreds or even thousands of amino acid residues. This size progression reflects the increasing molecular weight and complexity as more amino acids are added to the peptide chain, which is relevant in the context of peptide manufacturability and delivery mechanisms, such as synthetic long peptides (SLPs) and DNA vectors 1. Key considerations in peptide design include avoiding potential incidental DNA vector junctional epitope sequences and ensuring correct cleavage of the combined sequence by the proteasome, which can be addressed using tools like NetChop and pVACvector 1. The distinction between these categories is important in biochemistry and pharmacology, as peptide size affects properties like solubility, stability, and biological activity, with smaller peptides generally having better absorption profiles but shorter half-lives, while larger peptides and proteins have more complex structures and functions in the body. In the context of personalized immunotherapy, the choice of peptide size and delivery mechanism can impact treatment efficacy, with SLPs showing greater efficacy than short synthetic peptides due to their requirement for internalization and processing by professional APCs 1.
From the Research
Peptide Molecular Size Order
The order of peptides by molecular size from smallest to largest can be determined based on the number of amino acids they contain.
- Dipeptides, which consist of two amino acids, are the smallest peptides, with a molecular weight of around 100-300 Da, as seen in peptide 1, which has a molecular weight of 630 Da 2.
- Tripeptides, composed of three amino acids, are larger than dipeptides, with a molecular weight range of around 300-500 Da.
- Larger peptides, such as oligopeptides and polypeptides, have higher molecular weights, ranging from several thousand to millions of Da.
Molecular Size Comparison
Studies have shown that dipeptides and tripeptides have potential biomedical applications, including uses as drugs, flavor-active peptides, and ingredients in natural health products 3, 4.
- The molecular size of peptides can affect their biological functions, such as their ability to bind to cell surface sugars and induce cell uptake 2.
- The binding affinity of dipeptides to fatty acid membranes can also influence their colocalization with protocells 5.
Size-Related Properties
The physical and chemical properties of peptides, including their molecular size, net charge, solubility, and mechanism of action, can vary greatly 6.
- These properties can impact the biological activities of peptides, such as their antimicrobial functions and ability to deliver drugs and proteins 6.