In this paper, two basic amino acids, glycine (Gly) and alanine (Ala), are introduced. This is mainly because they can act as base amino acids and adding groups to them can generate other kinds of amino acids.
Glycine has a special sweet taste, so its English name comes from the Greek glykys(sweet). The Chinese translation of glycine not only has the meaning of “sweet”, but also has the similar pronunciation, which can be called the model of “faithfulness, achievement and elegance”. Because of its sweet taste, glycine is often used as a flavoring agent in the food industry to remove bitterness and increase sweetness. The side chain of glycine is small with only one hydrogen atom. That makes him different. It is a basic amino acid without chirality.
Glycine in proteins is characterized by its small size and flexibility. For example, the three-stranded helix conformation of collagen is very special. There must be one glycine for every two residues, otherwise it will cause too much steric hindrance. Similarly, the linkage between two domains of a protein often requires glycine to provide conformational flexibility. However, if glycine is flexible enough, its stability is necessarily insufficient.
Glycine is one of the spoilers during α-helix formation. The reason is that the side chains are too small to stabilize the conformation at all. In addition, glycine is often used to prepare buffer solutions. Those of you who do electrophoresis often remember that.
The English name of alanine comes from the German acetaldehyde, and the Chinese name is easier to understand because alanine contains three carbons and its chemical name is alanine. This is a simple name, as is the character of the amino acid. The side chain of alanine has only one methyl group and is slightly larger than that of glycine. When I drew the structural formulas for the other 18 amino acids, I added groups to alanine. In proteins, alanine is like a brick, a common basic building material that does not conflict with anyone.
The side chain of alanine has little hindrance and is located in the α-helix, which is a conformation. It is also very stable when β-folded. In protein engineering, if you want to mutate an amino acid without a specific target on a protein, you can generally mutate it to alanine, which is not easy to destroy the overall conformation of the protein.
Post time: May-29-2023