Peptide synthesis has become one of the essential things in bioorganic chemistry. Scientists use synthetic peptides to discover how living things work. Also, they help synthesize enzyme inhibitors and peptidomimetics.
In times past, peptide synthesis required much time and produced low yields. But in the new age, innovations, and peptide chemistry have made general research easier. However, not everyone understands the concept of peptide synthesis, which is why I have discussed everything you need to know about peptide synthesis. So, read on.
What are Peptides?
Peptides are short chains of amino acids that usually have between two and 50 amino acids in each one. Amino acids are the building blocks of proteins. However, proteins have more amino acids in them.
Due to the peptide’s small size, it is easier to break down than protein and easy for the body to absorb. Also, it can penetrate the skin and intestines more easily. Thus, allowing them to enter the bloodstream faster.
People often mix protein and peptides up because of their similarities, but they have differences. However, peptides have a lot fewer amino acids than proteins. Moreover, like protein, we can find peptides in the foods we eat.
So, we can find several supplements containing peptides on the market. These supplements are either gotten from food or synthesized by manufacturers.
What is Peptide Synthesis?
Peptide synthesis involves making short polypeptide chains by making one amino acid once. This process makes specific sequences that represent the epitopes of certain protein domains.
These domains may not have molecular structures on them. Then, the short sequences are injected into animals to produce antibodies against the polypeptide.
Chemically, we can make peptides in a solution or a solid phase. The process starts with forming an amide bond between an N-protected amino acid and another amino acid. The other amino acid has a free amino group and a protected carboxylic acid.
The carboxyl protecting group links to polymer support in solid-phase synthesis. After the amino-protection group of the dipeptide is removed, the next N-protected amino acid is added.
Peptide Synthesis Procedures
Though peptides occur naturally, scientists produce artificial ones for specific reasons. However, they synthesize those that are hard to express in bacteria. The most popular method for peptide synthesis is solid-phase synthesis.
The most popular method in peptide synthesis is the solid phase. However, scientists oppositely synthesize peptides. They start from the carbonyl group to the amino group. Then, they make peptides with the bond between the carbonyl group and the resin.
It is then deprotected and reacts with the N-protected amino acid’s carboxyl group. Now the solid phase has a dipeptide. After this, the peptide chain forms. After all these processes, the peptide cleaved from the bead.
They use 9-fluorenylmethyloxy carbonyl (Fmoc) and t-butyloxy carbonyl to protect the amino groups (Boc). Many amino acids have functional groups on their side chains, and they must protect these amino acids from the incoming N-protected amino acids.
In contrast to Boc and Fmoc groups, these groups must stay in place while making peptides. However, they are removed during deprotection.
Solution-phase synthesis was the only method in synthesizing peptides before solid-phase synthesis. However, SPPS can’t synthesize some peptides due to their chemical structure. This is where the solution-phase synthesis comes in. Though it is not common and scientists rarely use it, it has the same procedure as SPPS. However, it requires time because they extract the peptide from the solution.
As a result, SPPS has replaced solution-phase peptide synthesis in many labs. But, solution-phase peptide synthesis is still valid when making peptides for industrial use.
Advantages of Solid-Phase Synthesis over Solution-Phase Synthesis
Solid-phase peptide synthesis has several benefits over liquid-phase peptide synthesis when making synthetic peptides in large amounts. SPPS is faster, more efficient, and cheaper than solution-phase peptide synthesis, except for the synthesis of short peptide sequences, which takes longer and costs more.
Some of the benefits of SPPS are:
- To get rid of extra reagents and products, you can wash them away.
- The use of too many reagents speeds up reactions and completes them.
- Access to a broader range of low-volatility solvents and have much power.
- You can easily wash away extra reagents and products.
- Compatibility with automated synthesizers.
- Intermediates don’t need isolation or characterization.
The intermediates are not separated and do not need purification or analytical characterization. The reason is that the peptide is on a solid substrate in SPPS.
Applications of Synthetic Peptides
Synthetic peptides help make epitope-specific antibodies against pathogenic proteins. We can also use them to look into how proteins work and identify and characterize them. Synthetic peptides can also figure out enzyme-substrate interactions in important enzyme groups.
Moreover, it is common in cell biology to use homologous synthetic peptide sets to look into receptor binding. Scientists can make synthetic peptides look like natural peptides. Thus, using them to treat cancer.
Finally, synthetic peptides act as standards and reagents in mass spectrometry-based applications.
When producing peptides, the carboxyl group of the amino acid that comes in links to the early stages of the peptide chain. Modern peptide synthesis processes gain from synthesizing not only peptides found in biological specimens. They also gain from unique peptides helpful in optimizing a natural reaction.