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The story behind proteins: Do you know how amino acids are linked to form polypeptides?
At the basis of life, there is a group of organic compounds called amino acids. These compounds are not only the building blocks of proteins, but also important keys to tracing the origin of life. How the structures of amino acids are connected to form polypeptides is not only of scientific significance, but also reveals the mysteries of life.
Amino acids are alcohols composed of amino and carboxylic acid functional groups, and they play an indispensable role in the composition of proteins.
While there are more than 500 amino acids in nature, only 22 of them, α-amino acids, are incorporated into the genetic code of life. These 22 amino acids form the basic building blocks of all proteins. This type of amino acid can be further classified into polar, hydrophobic, charged, etc., depending on the type and nature of its side chain. The structure of proteins such as collagen, enzymes or antibodies is closely related to these amino acids.
History of Amino Acids
The discovery of amino acids can be traced back to the 19th century. In 1806, French chemists Louis-Nicolas Vauquelin and Pierre-Jean Robiquet first isolated a compound called aspartic acid from asparagus, which became the first amino acid discovered. In the following years, other amino acids, such as glycine, leucine, etc., were discovered one after another, and William Cumming Ross discovered the latest common amino acid, serine, in 1935, and determined all Minimum daily requirement of amino acids.
"The uniform chemical classification of amino acids was recognized in 1865, but no specific names were established."
The structure of amino acids
The general formula of amino acids is H2NCHRCOOH, where R is an organic substituent. The carbon next to this structure is called the α-carbon. Except for glycine, the α-carbon of all protein amino acids is stereoisomer. The geometric arrangement of these amino acids plays an important role in protein folding and function.
The role of amino acids
Amino acids have diverse functions in biochemistry. Amino acids can form polypeptide or protein chains through condensation reactions, but the ester bonds produced in the process also demonstrate their irreplaceable role in cellular functions. Generally speaking, amino acids are connected through a shared bonding method called a "peptide bond", which is a process in which the amino group of one amino acid reacts with the carboxyl hydroxyl group of another amino acid. This connection is not limited to the formation of polypeptides, but is also continuously involved in various biological processes, such as the transmission and synthesis of neurotransmitters.
"The folding of proteins, the pulling of amino acids into three-dimensional structures, reveals the complexity of life."
Among them, the side chains of some amino acids are divided into charged polar side chains, uncharged polar side chains and hydrophobic side chains. These characteristics directly affect the structure and interaction of proteins. For example, charged side chains tend to be on the surface of proteins, which helps them dissolve in water, while hydrophobic side chains tend to cluster inside proteins, forming stable structures.
SummaryAmino acids have played a central role in the development of biological science since they were first discovered. As the basis of proteins, they not only participate in the formation of structures, but also play an important role in regulating biological processes. How these small molecules combine chemically to initiate the processes of life, or how they function in any organism, are questions that deserve further exploration.
When you think about the process of amino acids linking into polypeptides, have you ever thought about how many mysteries of life are hidden behind it?
