How to Identify Small Molecule Peptides?

Peptides refer to a class of compounds with molecular structures between amino acids and proteins, which are composed of 20 natural amino acids in different ways. They are the general term for peptides from dipeptides to complex linear or cyclic structures. We call peptides composed of 2-10 amino acids oligopeptides, also known as small molecule peptides, with an average molecular weight of amino acids of 128 Da, so the molecular weight of oligopeptides is usually below 1000 Da. Those composed of 11-50 amino acids are polypeptides, and those with more than 50 amino acids are proteins.

 

 Important Roles of Small Molecule Peptides in Biology

1. They have biological activity and can act as signal molecules, hormones, or growth factors, participating in cell communication and regulation.

2. They also play key roles in cellular metabolism. For example, certain small molecule peptides can act as co-factors or inhibitors of enzymes, involved in the regulation of metabolic pathways.

3. They are closely related to the development of various diseases. For example, abnormal expression of certain small molecule peptides may be related to the occurrence of cancer, neurodegenerative diseases, or metabolic diseases.

 

The Methods of  Identification for the  Small Molecule Peptides 

1. Mass Spectrometry (MS)

MS is one of the most commonly used techniques for small molecule peptide identification. Through a mass spectrometer, small molecule peptides can be ionized and their mass-to-charge ratio (m/z) can be measured to obtain mass information of the peptide segments. Common mass spectrometry techniques include Electrospray Ionization Mass Spectrometry (ESI-MS) and Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry (MALDI-MS). These techniques can not only determine the molecular weight of small molecule peptides but also identify the sequence of peptide segments through database search and algorithm analysis.

 

2. High-Performance Liquid Chromatography (HPLC)

HPLC is a separation analysis technique that can be used for the purification and identification of small molecule peptides. By selecting the appropriate chromatographic column and mobile phase, peptides can be separated based on their polarity, hydrophobicity, and other characteristics. Combined with mass spectrometry, HPLC can be used for molecular weight determination and sequence identification of small molecule peptides.

 

3. Nuclear Magnetic Resonance (NMR) Technology

NMR is another commonly used method for small molecule peptide identification. By observing the resonance signals of hydrogen and carbon nuclei in small molecule peptides, information about their molecular structure can be obtained. NMR technology has unique advantages in determining the conformation, stereochemistry, and solution structure of small molecule peptides.

 

4. Amino Acid Composition Analysis

The amino acid composition of small molecule peptides is one of the important parameters for identification. Through acid hydrolysis or enzyme digestion methods, small molecule peptides can be hydrolyzed into individual amino acids, and the content of each amino acid can be measured using an amino acid analyzer. By comparing the amino acid composition with the known protein's amino acid composition, a basis for the identification of small molecule peptides can be provided.

 

In addition, small molecule peptides can be identified by methods such as N-terminal and C-terminal sequencing, database search comparison, etc., to determine the amino acid sequence.

 

MtoZ Biolabs uses Thermo's latest Obitrap Fusion Lumos mass spectrometer combined with Nano-LC nanoscale chromatography technology to provide high-resolution and highly sensitive identification of small molecule peptides. In addition, we have developed mass spectrometry-based protein N-terminal and C-terminal sequencing technology, where a single experiment can complete the determination of protein N-terminal and C-terminal sequences simultaneously. Please feel free to contact us for a free consultation on your project.