Small peptides don’t have any formal definition, but mostly, they don’t have much to offer in the way of the three dimensional structure. Some of them may have a fold or two, and it ends there. Small peptides depend on their amino acid sequences more than they depend on their three dimensional structure for their signaling.
As such, very minor changes in the sequences of their amino acids is sufficient to make a big difference with regards to the receptors that they can bind to. In some cases, a minute change in the amino acid is sufficient to completely alter how the small peptide works.
Back in the day, a lot of the research focused on massive protein and the larger peptides. This was because of the scientist’s notion that biologically active proteins had to be very large. It was also perceived that the best way to come up with therapeutics was to copy the existing proteins, but this was later discovered to not be true at all.
New studies are coming to the conclusion that small peptides are not just easy to make, but also can be used for a wide range of biological applications. The notion of mimicking naturally occurring proteins to make therapeutics is no longer pursued heavily and the focus of scientists is now shifting towards smaller peptides and the potential they have.
This shift is considered worthwhile since small peptides have been subjected to a wide range of applications ranging from heart medication to antibiotics, as well as to the development of solutions to certain killer diseases such as diabetes.
Studies have also shown that small peptides have anti-aging effects in animal models. Evidently, it can be safely concluded that the future of medicine will now involve a lot of small peptides, and they will no longer be ignored by scientists in favour of larger peptides.