What Are Peptides? Understanding Peptide Bonds

Let us start with the peptide basics!

Peptides are natural compounds present in all living organisms and are involved in a wide range of physiological processes. The most famous peptide is insulin (molecular structure of insulin on the right), an endogenous hormone for blood sugar regulation. Many other naturally occurring peptides are hormones as well, used as messengers between different systems of an organism to carry information (i.e. glucagon, encephalin, secretin). Others are antimicrobial peptides (i.e. defensin, magainin), or peptide toxins contained in animal venoms.

peptide bond

But what do they look like? Peptides are chains of amino acids (aka biological polymers or oligomers), from 2 to 100 aa and above. Amino acids are linked via peptide (or amide) bonds. Depending on their residue, there are 20 standard natural amino acids. Within a cellular environment, peptides may undergo post-translational modifications such as phosphorylation, acetylation, disulfide bridge cyclization, and many more. A peptide’s sequence, structural composition including its PTMs confer to a wide range of properties allowing the binding to receptors or ligands with a high affinity and specificity.

Peptide Synthesis

Thanks to their small size, peptides can be chemically synthesized, which is much easier than the expression and purification of recombinant proteins, which are prone to problems, such as proteolysis, incorrect folding, formation of inclusion bodies, or protein aggregation. Besides cost-efficiency and speed, all sorts of peptide modifications are possible. Finally, quality control ensures higher batch-to-batch consistency. These circumstances led the scientific community to extensively work on peptides and use them in many applications for basic research to pharmaceutical use.

At JPT we distinguish between resin-based synthesis and high-throughput synthesis on a SPOT-membrane, which allows for different quality grades (research use to clinical triels) and quantities (from 10µg to >1g). All formats and customizations are available in JPT's peptide synthesis service.

As previously mentioned, JPT offers a variety of peptide modifications, such as:

Biotinylated and Tagged Peptides
C-Terminal Modifications
Macrocyclic Peptides
Fluorescent Dye Labeled Peptides
Isotope Labeled Peptides
Long Peptide
Peptide Dimers
Peptidomimetics
(PTMs) Post-translational Modifications
Click Chemistry
Cyclic Peptides
Internally Quenched / FRET Peptides
Linker / Spacer / PEGylations
N-Terminal Modifications
Peptide Pooling and Library Service
Protein Conjugates /Immunogenic Peptides
Unnatural Amino Acids

Peptide Applications

Peptides have been used for decades in life-science research as laboratory reagents but also as therapeutic compounds, as drug delivery systems, as bio insecticides for agriculture, as biomaterials, as active compounds in cosmetics.

Peptides as Laboratory Reagents

Peptides are commonly used as reagents in all life-science research laboratories and the range of applications is endless. A few noteworthy examples are peptides which are used in vitro on skin cell samples to induce an irritation reaction (referred to as DRPA peptides), which allow cosmetic laboratories to test for irritation properties of compounds.

Peptides are also used in vaccine development to monitor the immune reaction of patients and understand whether a the vaccine has elicited an appropriate immune response.

They are also widely used to understand the binding properties of proteins. For example it is possible to modify some amino acids via chemical synthesis on a protein.

Moreover, they are employed as reference compounds in LCMS/MS SRM and MRM technologies, to accurately quantify and determine proteins, which allows to measure the expression of a biomarker in a tissue or perform DMPK studies of a biological drug. Read up on our peptides in proteomics.

Peptides as Therapeutic Drugs

More than 100 peptides are currently approved within pharmaceutical compositions such including insulin, semaglutide, ocreotide, oxytocin, exenatide, glucagon. Beyond that, thousands of peptides are in development for cancer vaccines, radiopharmaceutical targeted therapies, obesity, pain and more.

Peptides as Drug Delivery System

Peptides have become tools for delivering drugs to specific tissues. Macrocylic peptides containing unnatural amino acids have recently emerged due to progress in the chemical engineering and in silico AI design field. Thanks to their stability, high target specificity, cell-penetrating properties, and easy conjugation to drugs, cyclic peptides are attractive delivery candidates compared to antibody-drug conjugates.

Amphiphilic and hydrogel forming peptides are also used as biomaterials in drug delivery systems to encapsulate the drug and allow for its controlled release; examples include antibiotics, or antimicrobial coated surfaces.

JPT is a Berlin-based peptide producer based in Berlin sincemanufacturer founded in 2004. With already several mor than a millions of synthesized peptides synthesized per year, JPT is one of the most experienced companiesy in the world. Currently, thousands of peptides are commonly used by scientists and are available in our catalog. We synthesize all kinds of peptides upon request from 10µg up to several grams.