Protein

Protein can be found in muscles, bones, skin, hair, and almost any other organ or tissue in the body. It is the building block of enzymes, which power many chemical reations, as well as, haemoglobin that transports oxygen in your blood.

Amino acids are the twenty-plus basic building blocks that makeup protein. Because we can't store amino acids, our systems produce them in one of two ways: from scratch or by modifying other amino acids. The essential amino acids, which include histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine, must be obtained from food.

Functions of Protein

Proteins are important for the execution of complex processes and for the synthesis and regeneration of DNA.  Enzymes are proteins that digest food.  

Proteins are linked to the creation of a number of hormones that help keep the body's components in check. Cells use surface receptors to communicate with each other and with the outside world.  These receptors are composed of proteins.  

Antibodies are proteins in the body that the immune system uses to repair and heal the body after foreign pathogens have been introduced.  Proteins that allow cells and organs to interact.

The Structure of Protein

Peptide bonds are formed by the condensation of amino acids to form protein structures. Between the amine group of one molecule and the carboxyl group of the neighbouring molecule, a peptide bond (-CO-NH) is formed, followed by the removal of a water molecule. Otherwise, this is an amide linkage. A polypeptide chain is formed when peptide bonds are formed between more than ten amino acids. When the mass of a polypeptide chain surpasses 10000u and the number of amino acids in the chain exceeds 100, a protein is created.

What are The Four Types of Structure of Protein?

1. Primary Structure

• The primary structure is defined as the sequence of amino acids that compose a polypeptide chain. Proteins are divided into 20 distinct amino acids. The order in which amino acids exist in a protein is known as its primary sequence.

2. Secondary Structure

• The backbone's regular, repeating folding patterns are referred to as a protein's secondary structure. The two most common folding patterns are the alpha helix and the beta-sheet.

• α – Helix: The Helix is one of the most popular ways for a polypeptide chain to generate all potential hydrogen bonds by twisting into a right-handed screw and hydrogen-bonding the -NH group of each amino acid residue to the -CO of the adjacent helix turn. The polypeptide chains formed a right-handed screw as they twisted.

• β – pleated sheet: The chains of polypeptides come next to one another and are then connected by H-bonds in this manner.  All peptide chains are stretched to nearly maximum extension and then arranged side by side in this structure, which is held together by intermolecular hydrogen bonds. The structure resembles the pleated folds of drapery that is why it is called a β – pleated sheet.

3. Tertiary Structure

• The entire polypeptide chain folded into a precise 3D shape is called tertiary structure. Enzymes usually have a compact spherical tertiary structure.

4. Quaternary Structure

• Many proteins are composed of several polypeptide chains. The quaternary structure of a protein describes how the various subunits are packed together to produce an overall structure.

More on The Topic

Proteins are large, specialized, and complex molecules that include oxygen, carbon, nitrogen, hydrogen, and sometimes sulfur. Proteins are composed of thousands of smaller units known as amino acids which are attached together to form a long chain of polypeptides (proteins). 

There are a total of 20 different types of amino acids that combine together to make proteins. These amino acids are identical but have different side chains. The amino acid sequence of proteins determines the unique 3-dimensional structure of each protein and its specific function. The function of the protein in the human body is that it is required for the structure, regulation, and function of the tissues and organs of the body.

(Image will be Uploaded soon)

The structure of a protein is a 3-dimensional arrangement of amino acid residues that link up to form polypeptide chains. Proteins are polymers whose structure is formed by the link-up of several such long chains that are made from amino acid (monomer of protein)  sequences. The position and property of amino acids decide the ultimate structure and function of the protein. 

(Image will be Uploaded soon)

Amino acids are substituted methane, in which the alpha-carbon valencies are occupied by a carboxyl group (-COOH), amino group (-NH₂), hydrogen, and a variable R-group. A variety of amino acids are present depending on the R-group, out of which 20 are used in the making of the polypeptide chain. The structure of a protein is better described by using its types.