All proteins perform a unique functionin cells. But to do that, they must first be transported to the proper location. Therefore, there is a special part of the protein that governs this process.
As you might know, proteins are produced by cells using the genetic information from DNA. Through the production and subsequent processing, the protein is equipped with structural elements needed for it to end up in the right location. We will return to this aspect later – first, let’s go over the widerange of functions and processes thatinvolve proteins.
Proteins are inevitable in normal body function
There is a clear reason why you should include protein (or their building blocks, amino acids) in your everyday diet: Proteins facilitate all known chemical reactions in the human body. Therefore, the list of functions is extremely long, but certain examples illustrate the variety in how the body uses protein:
- Enzymes are the proteins that speed up all reactions in the body and form new molecules from the genes in DNA.
- Antibodies are Y-shaped proteins that recognize specific, foreign cells, such as viruses and bacteria. They target these cells for destruction by the immune system.
- Hormones are signaling proteins, which coordinate processes across cells, tissues and organs.
We could list manyother examples, but let’s insteadmove on and investigate the simple structure of a protein.
A protein might look complex, but it’s just a long sequence tangled together
There are two distinctive ends of a protein – the C-terminal and the N-terminal.
Picture a protein as a long sequence of amino acids, like beads on a string. The string is then folded together in a manner that at first seems messy and randomly mixed. However, every fold and turn are there for a reason, since the 3D-structure determines the function of the protein. Thus, both ends also play a crucial role in the protein’s skills in and outside of the cell.
The N-terminal is important for protein survival
The beginning of the protein sequence is called the N-terminal and gets its name from the free amine group (-NH2) on every amino acid. The C-terminal is similarly the name derived from the carboxylic acid on the opposite end of the amino acids.
When a protein is first stitched together by connecting amino acids, it happens from the N-terminal to the C-terminal. The first amino acid is named the N-terminal amino acid.This amino acid often determines how likely it is that the protein breaks down when it isno longer needed by the cell. Furthermore, the N-terminal end directs the protein to the proper location in the cell where it performs or fulfills its purpose.
Since the N-terminal sequence plays these important roles, it is of interest for biopharmaceutical companies to check it during the quality control of medicine. This is typically done by Edman degradation, which quickly and accurately determines the N-terminal amino acid and the next 10-20 amino acids.