In the recent wake of in-depth studies about peptides and proteins, a novel term has been introduced into the fields of medicine and biochemistry-short peptides. From the name, it feels as if the term has been assigned to peptide chains having concise length since we all know that proteins are formed by repeated peptide units, where each peptide is considerably large. However, the latest studies have proven this entire concept to be different. These have clearly stated that the exact definition of short peptides is contradictory, and it entirely depends on the reference one is taking. Therefore, an in-depth analysis is required to know more about this unique discovery. 

Amino Acids, Peptides, Short Peptides, and Proteins

When a carboxylic group reacts with the amine compounds, they undergo a dehydration reaction due to which the acid loses a hydroxyl ion while the amine loses the hydronium ion. As a result, an amide compound is formed, also termed an amino acid. With the help of a polymeric condensation reaction, two amino acid molecules join with each to form a more giant or dimeric molecule, also known as the peptide. The bond between the amino acids is known as the peptide bond.

Now, as these peptides join, they form the proteins. The term ‘peptide’ is wholly based on reference and is classified into several other terms based on the number of amino acids present. These can be classified into two forms:

• Oligopeptides: These contain about two to forty amino acids and usually have a branched structure. 
• Polypeptides: In polypeptides, the number of amino acids is more than 40, resulting in unbranched structures. 

When the polypeptides gain many amino acids, they are arranged in an appropriate structure known as proteins. However, according to several sources, it is believed that proteins cannot have more than a hundred amino acids. 

Therefore, short peptides are chains where the amino acids will be less than 45 in most cases. If any peptide chain has two to five amino acids, they will be termed ultra-short peptides. 

How is a short peptide synthesised?

The short peptides are synthesised by two main methods-liquid-based and solid base. Even though both these methods have been classified as different, they follow the same rule-i.e., condensation of the amino acids and the loss of one water molecule.

In the solid-state synthesis process of short interfering peptides, the amino acids join with each other at the C-terminus of an insoluble polymer. On the other hand, 4 amino acids combine to form the tetrapeptides when a solution is added as the base to facilitate the polymeric reactions. 

What are the advantages of studying more about the short peptides?

• It is easy to find these peptides since they are composed of a few amino acid molecules. 
• When synthesised via in-vivo practice, the short peptide can help study the bigger peptide chains and tertiary proteins formed both in the human body and nature. 
• It is straightforward to understand the structures and their dependencies in the case of the short peptides. 
• During the artificial preparation, it is straightforward to modify the peptides and understand how they will behave on the addition and subtraction of different compounds. 
• Proteins and long peptide chains are subjective to temperature, and therefore they undergo a denaturation process. However, the short peptide molecules have simple structures with solid bonds. Therefore, they are highly stable. 
• The ultra-short interfering peptides can easily penetrate the cell membranes, which isn’t possible for the long peptide chains and the proteins. 
• The toxicity level of these short molecules of peptides is shallow, owing to which they can be used in the medicinal field. 
• One of the significant advantages of studying short peptide molecules is their ability to target specific biological processes. 

Are there any challenges with the study of short peptides?

There are several challenges with the study of short peptides, especially since it is pretty hard to identify which peptide molecules can be classified solely under this category. 

• When the short peptide molecules are added to the plasma solution for in-vivo studies, they can easily undergo the denaturation process and disintegrate. 
• They have a lesser affinity for binding with other molecules, so the integrity of the original molecules can be lost. 

Conclusion 

 With the introduction of short peptides, it will be possible to analyse the peptide behaviour of larger chains in-depth and understand their utility in treating several healthcare problems. The study of short peptides will create a revolution in the biochemistry and medicine industry. Even though the concerned field is still in the budding stage, it is truly a challenge to understand how they will behave in cases of different situations. Besides, there are concerns about the cancerous or mutation properties of the short peptide molecules when they are synthesised artificially. Also, if the shorter peptides are used to form the larger ones, questions will pop up concerning their impacts on cell penetration power and your body’s immunity.