First, researchers collect gastric juice samples. This is done through careful extraction from the stomach, often using specialized medical equipment. The gastric juice contains many different proteins and peptides mixed together.
Next comes a crucial step called fractionation. Think of this like sorting through a mixed bag of items - researchers separate the gastric juice into different parts based on specific properties. They commonly use a technique called chromatography, where the mixture flows through a special column that separates molecules based on their size, charge, or other chemical properties. Each separated portion is called a fraction.
After getting these fractions, researchers test each one to see which has biological activity - in this case, which fraction shows healing or protective effects. This testing process helps identify which fraction contains the peptide of interest.
Once they identify the active fraction, researchers use more precise separation techniques to isolate the specific peptide. This often involves additional chromatography steps or other separation methods that can distinguish between very similar molecules.
The final step is determining the peptide’s structure. Scientists use techniques like mass spectrometry and protein sequencing to identify the exact sequence of amino acids that make up the peptide. This is how they would have determined that BPC-157 is made up of 15 specific amino acids.