How to Determine the Amino Acid Sequence of Proteins

Determining the amino acid sequence of a protein involves analyzing the structural information of the protein to deduce the order of its amino acids. The main technical approaches include protein cleavage, amino acid separation, and finally, amino acid sequence analysis. Protein cleavage can be achieved through enzymatic or chemical methods, resulting in smaller peptide fragments that are further separated using chromatography or electrophoresis. For the separated amino acid sequence analysis, commonly used methods are Edman degradation and mass spectrometry. Edman degradation is a classical sequencing method that removes amino acids one by one and detects their properties to deduce the original sequence. Mass spectrometry, a more commonly used method, obtains the amino acid sequence information of a protein by measuring the mass-to-charge ratio of molecules.

In the process of determining the amino acid sequence of proteins, researchers need to consider the complexity of protein structures and the scarcity of samples. Therefore, there are extremely strict requirements for protein separation and purification technologies, as well as for the processing and analysis of sequencing data.

Common Issues:

Q1: What is Edman degradation? How is it performed?

A: Edman degradation is a classical method for determining the amino acid sequence of a protein. It involves sequentially removing the N-terminal amino acid of the protein and then determining the type of amino acid removed using specific detection methods (such as chromatography) to deduce the protein's amino acid sequence.

Q2: What is the role of mass spectrometry in determining the amino acid sequence of proteins?

A: Mass spectrometry is currently the most commonly used technique for determining amino acid sequences. By measuring the mass-to-charge ratio of molecules, it obtains the amino acid sequence information of proteins. The advantages of mass spectrometry are its high sensitivity, high precision, and high throughput, allowing for rapid sequencing of a large number of samples.