Protein N-terminal and C-terminal Sequencing Methods Analysis

Protein N-terminal and C-terminal sequencing are methods of analyzing the arrangement of amino acids in protein sequences, especially the starting and ending positions of the sequence. This sequencing can provide important information about the origins, structure, and functions of the protein.

 

N-Terminal Sequencing (Edman Degradation)

Edman degradation is a classic method of protein N-terminal sequencing. In this process, the N-terminal amino acids of a protein are selectively removed one by one, and identified. The process can be carried out consecutively, yielding the first few residues of the amino acid sequence of the protein.

 

1. Advantages

High degree of accuracy and sensitivity.

 

2. Disadvantages

The process is relatively slow, and it is difficult to sequence long-chain proteins.

 

C-Terminal Sequencing

Unlike N-terminal sequencing, the methods for C-terminal sequencing are not as mature and common. The C-terminal of a protein can usually be identified by enzymatic or chemical cutting. Using specific enzymes, such as carboxypeptidase, amino acids can be gradually removed from the C-terminal of a protein. By analyzing the removed amino acids, the sequence of the C-terminal can be inferred.However, this method is often limited by the structure of the protein and the location of the enzymatic cut, and may not be suitable for all proteins.

 

With the advancement of mass spectrometry technology, especially tandem mass spectrometry, the complete sequence analysis of proteins has become easier and more accurate. By enzymatically cutting proteins and then sequencing the resulting fragments using mass spectrometry, the entire amino acid sequence of a protein can be reconstructed, yielding information on the N-terminal and C-terminal.