How to Sequence a Peptide

Peptide sequencing refers to the determination of the amino acids that make up the structural sequence of a peptide chain. Revealing this information is crucial to discovering the function and structure of a protein in the cell, which in turn is valuable to biomedical research applications.

By understanding how to sequence a peptide, scientists can develop advanced, proteomics based solutions to fight diseases. This blogpost will answer how to sequence a peptide by reviewing two primary methods of peptide sequencing. This piece will first give a brief summary of the traditional mode of peptide sequencing known as Edman degradation and move to focus on a more recent innovative technique – mass spectrometry – that bolsters the relevance and impact of proteomics.

Traditional Peptide Sequencing by Edman Degradation

In the 1950s, Frederic Sanger successfully sequenced a complete protein, winning him the Nobel Prize in Chemistry. To add to Sanger’s contributions to the field of peptide sequencing, Pehr Edman developed a method to identify a sequence of amino acids in a peptide or protein. Dubbed Edman Degradation, this methodological procedure was then automated by Edman and his colleagues in the late 1960s. This advancement set the foundation for research into more streamlined and effective methods of peptide sequencing.

Edman degradation is a repetitive procedure where a series of chemical reactions cleaves and identifies an amino acid from the N-terminus of a peptide chain. Then, the next amino acid is revealed and undergoes the same chemical reactions as the one before it, the degradation process revealing each peptide building block in sequence from the N-terminus to the C-terminus.

Though Edman degradation became a standard for peptide sequencing since its development, it is limited by multiple drawbacks. Specifically, the time-consuming technique had difficulty sequencing long peptides and failed when the N-terminus was in any way altered or blocked as the chemical reactions could not access the amino acids to cleave and identify. However, innovations in technology have offered an alternative method for how to sequence a peptide that circumvents the restraints of Edman degradation. This technique is mass spectrometry and will be discussed further in the next section.

Mass Spectrometry Performs Highly Innovative Peptide Sequencing

Mass spectrometry has either been used in conjunction or largely replaced Edman degradation as the primary technology for peptide sequencing. This is because the innovative process is highly sensitive and fragments long proteins into manageable and quickly sequenced peptides. Also, mass spectrometry can still sequence peptides even with modified or blocked amino terminuses. Therefore, mass spectrometry can sequence larger peptide samples more quickly, effectively and accurately.

Peptide sequencing by mass spectrometry is conducted by the following steps. First, proteins are digested into smaller peptides. These peptides are transferred into a mass spectrometer through a liquid chromatography column and ionized before analysis.

The mass spectrometer then determines the mass-to-charge ratios of the sample ionized peptides and can characterize them based on this information. Database matching is then performed to identify amino acid sequences. Mass spectrometry enables the rapid identification and quantification of peptides and can provide valuable information on the expression and function of proteins.

Biognosys Provides Advanced Peptide Sequencing Technologies for Disease Research

An expert in mass spectrometry proteomics, Biognosys presents cutting-edge solutions for how to sequence a peptide. Biognosys specialists have developed mass spectrometry technology to increase the efficiency and precision of peptide sequencing.

For example, the patented Hyper Reaction Monitoring (HRM)  technology can identify differentially expressed protein or highly multiplexed protein quantification on a proteome level. Equipped with advanced Biognosys products and services, researchers in academia and industry alike can harness the increased potential of proteomics in the laboratory.

To find out more about peptide sequencing for disease research contact us today.