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Unveiling the secrets of amino acids: Why are there only 22 α-amino acids as the building blocks of life?
When exploring the nature of life, amino acids are often the focus of research. Amino acids are organic compounds containing amino and carboxylic acid functional groups. Although there are more than 500 kinds of amino acids in nature, only 22 kinds of α-amino acids are incorporated into biological proteins in living bodies. The emergence of these amino acids played an indispensable role in the formation and development of life.
Amino acids are the building blocks of life and were crucial to the origin of life.
There are many ways to classify amino acids, based on the functional group positioning of their core structure (such as α, β, γ amino acids, etc.), as well as characteristics such as polarity, ionization, and side chain type (such as aliphatic, acyclic, aromatic, etc.) Classify. These amino acids, the residues of proteins, form the second largest component of human muscles and other tissues, after water. In addition to being building blocks of proteins, amino acids are also involved in a variety of processes, including neurotransmitter transport and biosynthesis, and their role cannot be underestimated.
The history of amino acids
The first discoveries of amino acids date back to the early 1800s. In 1806, French chemists Louis-Nicolas Vauquelin and Pierre Jean Robiquet isolated a compound from asparagus and named it Asparagine became the first amino acid discovered. Subsequently, cysteine, glycine, and leucine continued to be discovered. Finally, in 1935, William Cumming Ross discovered taurine (Threonine) for the first time and established the minimum daily requirements for various amino acids. .
Structure and properties of amino acids
Generally speaking, the general formula of α-amino acid is H2NCHRCOOH, where R is an organic substituent. These 22 amino acids are the building blocks of natural proteins and combine to form a variety of peptides and proteins. The properties of many amino acids, such as polarity, hydrophilicity, or hydrophobicity, have a significant impact on the formation and interactions of protein structures.
In water-soluble proteins, hydrophobic residues are usually located in the interior of the protein, while hydrophilic side chains are exposed to aqueous solution.
Types of amino acids
Amino acids can be divided into several categories based on the polarity of their side chains, including charged polar side chains, uncharged polar side chains, and hydrophobic side chains. In particular, charged amino acids such as aspartic acid and glutamic acid are usually on the surface of proteins, promoting their solubility in water and forming salt bridges that maintain the protein structure.
Function of amino acids
Amino acids are not only the building blocks of proteins but also play multiple roles in biochemical processes. For example, they are also crucial in the production of neurotransmitters. A few amino acids, such as taurine and selenoine, are incorporated into proteins through special synthesis mechanisms, which shows the diversity of amino acids and their complexity in biology.
Summary
The diversity of amino acids allows them to adapt to various biological functions and processes, from composing proteins to affecting biological chemical reactions, all reflecting the importance of amino acids. So why did nature choose these 22 amino acids as the basic units of life, while other amino acids were excluded? Does this imply that the choice of amino acids is deeply related to the origin of life?
