Know what you need to know about Custom Peptide Synthesis

Custom peptide synthesis is the large scale production of peptides in industries for use in biochemistry, pharmacology, molecular medicine and biotechnology. These oligopeptides produced artificially are used to study the protein interfaces, for the production of some antibodies.

The process of linking two or more amino acids by amide bonds is called peptide synthesis. It happens when the C-terminus amino acid reacts with amino group N-terminus of another amino acid. In the lab, they are produced by either solution phase technique or by solid phase technique. But the yield in both the process is typically slow and cannot be used for the production of peptides in large scale commercial purposes.

An understanding of Linear vs. Convergent Synthesis

The linear method is used for synthesizing peptide compounds which are up to five amino acids in length. Here, each amino acid is added to the sequence until the compound is produced.

For longer peptides which are more than 100 amino acids, this process would be too slow. In the peptide synthesis method or the convergent method, the small segments are synthesized simultaneously and then assembled with one another to form the compound.

Example of some Protecting Groups

α-Amino Group Protection

The protecting group used in the commercial process is Boc and benzyloxycarbonyl (Z) groups. The Boc group is removed by acids like trifluoroacetic acid (TFA). The Z group is removed by reduction

Carboxyl Group Protection

Best protecting agent for the carboxyl group is either benzyl or t-butyl ester. They are removed in the same way as the Z group and the Boc group hence they must be orthogonal to the α-amino protecting group.

Side Chain Protection

Minimum side chain protection is desirable to minimize the number of steps. But minimising side-chain protection makes peptide compounds hydrophilic which complicates the extraction.

Coupling of individual amino acids

The most common coupling agents used are carboxylic-carbonic anhydrides, carbodiimides and uronium reagents.

Coupling of Segments

 To counter the risk of racemisation during coupling of segments there are various methods like carbodiimide method with an added nucleophile, isobutyl chloroformate with or without an added nucleophile.

Here are some Tactics for Scaling Up

Chemical and Technical Aspects

In any multistep process, the number of processes should be minimised. But in custom peptide synthesis method yield efficiency is given maximum priority. It also means a longer time for synthesis. For the commercial purpose, the convergent technique is preferred. The problem of isolated intermediaries to be in solid form is solved by precipitation and chromatography.

Commercial and Economic Aspects

The choice of using pre-activated or non-activated amino acids is simple. Pre-activated amino acids are expensive but reduce synthesis time. Non-activated amino acids are cheap but they increase the synthesis time. Also, raw materials should be used in their stoichiometric amounts to reduce costs.

Safety and Environmental Aspects

It is important that the chemicals used in the synthesis are not harmful to humans and the environment.

There are various methods and techniques for commercial production of peptides. But other factors like costs, adherence to safety regulations and output efficiency are important as well.