Did you know that proteins are the functional elements of our organism? They are composed of amino acids that are encoded by our DNA. Find out more about proteins and amino acids in this article!
Amino acids are organic molecules found in nature that are essential for life. These molecules are the building blocks of proteins, which are essential for the functioning of all cells and tissues in the body.
There are 20 different amino acids that are used to build proteins. Each amino acid is composed of an amino group (-NH2), a carboxyl group (-COOH), and a variable side chain (R group), which gives it its unique identity. The side chain can be aliphatic, aromatic, hydroxylated, sulfur or charged, and is what determines the chemical and physical properties of each amino acid.
Amino acids are classified into two main categories:
- Essential amino acids: Essential amino acids are those that the body cannot produce on its own and must be obtained through the diet.
- Proteins are biological macromolecules essential for life. They perform a wide variety of functions in living organisms, such as biochemical reactions catalysis, cell-to-cell communication, defense of the body against disease, and building cellular structures.
Proteins are biological macromolecules essential for life.. They perform a wide variety of functions in living organisms, such as catalyzing biochemical reactions, communicating between cells, defending the body against disease and building cellular structures.
Proteins have many important functions in the body among which we can highlight the functionalities of:
- Structure: Proteins are important components of the body's cells, tissues, and organs. For example, collagen is a protein that provides structure and elasticity to skin, bones, tendons, and cartilage.
- Enzymatic: Proteins can also act as enzymes, which are molecules that speed up chemical reactions in the body. For example, digestive enzymes that break down food so that it can be absorbed and used by the body.
- Transport: Some proteins, such as hemoglobin, are responsible for transporting important molecules such as oxygen and carbon dioxide in the blood.
- Immunity: Proteins can also act as antibodies, which are molecules that help the immune system fight infection and disease.
- Hormonal: Some proteins act as hormones, which are molecules that regulate various functions in the body such as insulin that regulates blood sugar level.
- Contractile: Contractile proteins, such as actin and myosin, are responsible for muscle contraction and movement.
- Storage: Some proteins can store important molecules, such as iron in ferritin.
- Regulation: Other proteins can regulate gene expression, such as histones.
All the functions mentioned above are possible thanks to the structure of proteins. The structure of proteins can be described at four different levels: primary, secondary, tertiary and quaternary.
Primary structure of proteins
It is the linear sequence of amino acids that make up protein. Amino acids are the building blocks of proteins and are linked by peptide bonds to form a linear chain. The amino acid sequence is determined by the genetic code present in the DNA.
There are 20 different amino acids that are used in protein synthesis, and each has a unique chemical structure. The sequence of amino acids in a protein determines its three-dimensional structure and biological function.
The primary structure is essential for the stability and function of the protein. Any change in the amino acid sequence can significantly affect the structure and function of the protein.
Errors in the amino acid sequence can have serious health consequences, as in the case of genetic diseases caused by mutations in the genes that code for proteins.
Secondary structure of proteins
This is the locally folded structure that is formed within a polypeptide due to interactions between atoms in the polypeptide chain.
This structure is due to the formation of hydrogen bonds between the amide and carboxyl groups of amino acids. The two main types of secondary structures are alpha helices and beta sheets.
Tertiary structure of proteins
The tertiary structure is essential for the function of proteins, since it determines the interaction of some proteins with others.
The tertiary structure is essential for protein function, as it determines the interaction of proteins with each other..
Quaternary structure of proteins
This structure is characteristic of proteins composed of several polypeptide chains called subunits. The union of these subunits gives rise to the quaternary structure. Proteins lacking subunits will lack of quaternary structure.
Thus, the quaternary structure of proteins refers to the three-dimensional organization of two or more individual protein subunits that come together to form a complete functional protein. That is, it is the way individual protein subunits are organized and held together to form a complex protein.
Among the proteins with quaternary structure we find hemoglobin, which consists of four identical subunits.