Proteins Secondary Structure, And Proteins Type

Proteins Secondary Structure And Proteins Type

Proteins Secondary Structure, And Proteins Type


Proteins Secondary Structure, And Proteins Type: Protein is an important nutrient found in food which is a very essential substance for the human body.

It is a large molecule i.e. polymer, which is made up of many smaller units of amino acids, these smaller units are called monomers. That is, monomers are those organic compounds whose polymerization results in polymerization.

The primary structure of a protein is the amino acid sequence of the protein, which is linear. It forms the polypeptide chain of the protein. Each amino acid binds to adjacent amino acids via a peptide bond. Because of the chain of peptides bond in the amino acid sequence, it is called a polypeptide chain. An amino acid is one of a pool of 20 essential amino acids in a polypeptide chain.

The codon sequence of a protein-coding gene determines the order of the amino acids in the polypeptide chain. The coding sequence is first converted into mRNA and then decided to form the amino acid sequence. The former process is transcription, which takes place inside the nucleus. RNA polymerase is an enzyme involved in transcription. The latter process is translation, which takes place in the cytoplasm. Ribosomes are organelles that facilitate translation.

Proteins Secondary Structure

The secondary structure of a protein is either an α-helix or β-sheet that is formed from its primary structure.

It entirely depends on the formation of hydrogen bonds between the structural components of amino acids. Both the α-helix and the β-sheet contain regular, repeated patterns in the backbone.


The assembly of the polypeptide backbone around an imaginary axis in a clockwise direction forms the α-helix. This occurs through the formation of a hydrogen bond between the oxygen atom in the carbon atom group (C = O) and the hydrogen atom in the amino group (NH) of the fourth amino acid of the polypeptide chain.


In the β-sheet, the R-group of each amino acid alternately points up and down the backbone. Hydrogen bond formation occurs between adjacent strands, which are adjacent. This means that the oxygen atom of the carbonyl group of one strand forms a hydrogen bond with the hydrogen atom of the amine group of the other strand. The arrangement of the two strands can be parallel or antiparallel. Parallel strands are more stable.

Protein Types

Proteins can be classified into three types:

  1. Complete protein
  2. Incomplete protein and
  3. Complementary protein

Complete protein

These types of protein-rich foods contain all the essential amino acids. They are mostly found in animal products or foods such as meat, dairy products, eggs, etc.

Incomplete protein

Proteins or protein-rich foods that lack at least one or more of the essential amino acids are called incomplete proteins. All plant proteins are incomplete proteins, such as peas, beans, nuts, and grains, etc.

Complementary protein

They are made by mixing two or more foods with incomplete proteins. These can be used to supply complete proteins.

For example, rice and beans are included with peanut butter.

Functions Of Proteins

  1. Protein is required for the functioning of every cell in the body.
  2. Proteins play an important role in transporting and storing molecules throughout the body.
  3. Protein is essential for repairing cells.
  4. assist in the formation of new cells
  5. to protect the body from viruses and bacterial infections in the form of antibodies
  6. performing important functions as enzymes and hormones (insulin)

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