A custom peptide is a small polymer of amino acids that is synthesized chemically upon demand. Such peptide services are often provided by biotechnology companies. Many peptides have biological functions, such as hormones or toxins. Synthetic peptides can be used in research, medicine, or for commercial use. Often a large peptide library is made to screen for peptides with particular functions, such as the ability to act as a hormone or a vaccine.
Amino acids are linked together in a chain to form peptides or proteins. Traditionally, chains that are composed of 50 or fewer amino acids are known as peptides. Longer chains are referred to as proteins. The chains are connected by peptide bonds between the N terminus of one amino acid and the C terminus of the next.
The main difference between natural amino acid assembly, mediated by ribosomes reading the code on messenger RNA, and the assembly of amino acids synthetically is the order in which the units are assembled. Natural peptide synthesis starts with the N terminus, while the synthesis of a custom peptide begins with at the C terminus. The final molecules are identical.
There are many reasons why one might want access to a custom peptide. Obtaining peptides from natural sources can be highly labor intensive and use valuable biological materials. In the burgeoning field of peptidomimetics, many peptides with valuable functions do not exist in nature. They can only be obtained through the synthesis of custom peptides. For instance, a peptide containing unnatural amino acids is likely to have different biological effects than one with amino acids found in nature.
Peptide synthesis in the laboratory can be difficult for those researchers who do not specialize in it. Many contract this task out to peptide synthesis companies who can provide the desired custom peptide at a reasonable cost. This can save the researcher an enormous amount of time and set-up costs for the peptide synthesis.
There are numerous peptide companies that specialize in the production of peptides or peptide libraries for researchers. A peptide library consists of a mixture of peptides designed to the researcher’s specification. For instance, if the researcher works with hormones, the peptides would be engineered to have a variety of sequences that might yield new hormones.
With the advent of combinatorial chemistry, one can focus on developing a large number of peptides with structural similarities. Such a library can be screened for active compounds. If the principle of peptidomimetics is used to design unusual peptides, the peptide library is much more likely to include biologically active peptides.