Protein as a Biomolecule

Tuesday, May 2, 2023 Pranabjyoti Das 1

ARUNODOI JUNIOR COLLEGE

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BIOMOLECULESProtein

Structure & Functions


What is Protein ?Proteins are some important biomolecules

found in all living cells. Proteins are some polymers of Amino Acids.Proteins are found in our body as Muscles,

Enzymes, Hormones, Antibodies and many more.

We get some proteins into our body as food like Meat, Fish, Eggs, Soya etc.

Some proteins can be synthesized by the Ribosome of our cells.


Some Proteins under Electron Microscope

AntibodyMyoglobin


Give examples of proteins that are important to the structure of

organisms….Some proteins are important to the structure of organisms

Question For You:

Our hairSpider silk

Fibers of Tendons and Ligaments

Our Muscles etc.


Name some Proteins that serve the following specific functions….

For You Again

Name a Protein that carry oxygen in our body.Ans : Haemoglobin

Name a Protein that provides us with immunity.

Ans : AntibodyName a Protein that serves as

enzyme.Ans : Pepsin, Renin, Trypsin etc

PROTEIN STRUCTURE

An α-amino acid. The CαH atom is omitted in the diagram.

CO-R-N rule

Two amino acids Bond angles for ψ and ω

http://en.wikipedia.org/wiki/File:Proteinviews-1tim.png

http://en.wikipedia.org/wiki/File:A-amino-acid.png

http://en.wikipedia.org/wiki/File:Amino-CORN.png

http://en.wikipedia.org/wiki/File:2-amino-acids.png

http://en.wikipedia.org/wiki/File:Fipsi.png


Proteins are made of some Amino Acids

Amino Acids are biologically important organic compounds containing one Amino group (-NH2), one

Carboxyl group (-COOH) and a side chain with one R group.

Amino Acid

An Amino Acid Has…

20 different Amino Acids make up all

our Proteins

Central carbon atom

An amino groupA carboxyl group

An R-group

The R-group varies from one amino acid to another

A hydrogen atom


Amino Acids Are Of Two Types

Non-Essential Amino Acids :

The Amino Acids which can be synthesized in our body by Ribosomes. Example: Alanine, Glutamate, Proline etc. Essential Amino Acids:

The Amino Acids which are never synthesuzed in our body and we need to get them in our food. Example: Methionine, Valine, Leucine etc.

There are only 20 Amino Acids which link together with each other by Peptide Bond to form Protein

Structure of Amino Acid

Amino acids have an amino group and a carboxyl group

Both groups are covalently bonded to the center carbon atom, called the alpha carbon.

Bonded to the alpha carbon is a hydrogen atom and a chemical group called the ‘R group’.

The amino acid type differs depending on the structure of the R group.


Amino Acids are linked to form Peptide Bond

Two amino acids join together by a condensation reaction

Water molecule removed is removed when a carboxyl group binds to the nearby amino-group

Resulting covalent linkage is called a peptide bond.


Formation of Peptide Bond


Proteins are biochemical compounds consisting of

one or more polypeptide chains typically folded into

a globular or fibrous form in a biologically functional way.

Proteins were first described by the Dutch chemist Gerardus Johannes Mulder and named by the Swedish chemist Jöns Jacob Berzelius in 1838. Early nutritional scientists such as the German Carl von Voit said

that protein was the most important nutrient for maintaining the structure of the body, because it was

generally believed that "flesh makes flesh.

More About Proteins..


Primary Structure of Protein

The primary structure refers to amino acid sequence of the polypeptide chain. The

primary structure is held together by covalent or peptide bonds, which are

made during the process of protein biosynthesis or translation. The two ends of the polypeptide chain are referred to as the

carboxyl terminus (C-terminus) and the amino terminus (N-terminus) based on the nature of the free group on each extremity. Counting of residues always starts at the N-terminal end (NH2-group), which is the end where the amino group is not involved in a

peptide bond.


Secondary Structure of Protein

These secondary structures are defined by

patterns of hydrogen bonds between the main-

chain peptide groups. They have a regular geometry,

being constrained to specific values of the

dihedral angles ψ and φ on the Ramachandran plot. Both the alpha helix and

the beta-sheet represent a way of saturating all the

hydrogen bond donors and acceptors in the peptide

backbone.


Tertiary Structure of ProteinProtein tertiary structure is the 3D shape of a protein. The tertiary structure will have a single polypeptide chain as "backbone" with

one or more protein secondary structures. Amino acid side chains may interact and bond in a number of ways. The

interactions and bonds of side chains within a particular protein determine its tertiary structure.


Quaternary Structure of Protein

Many proteins are made up of multiple polypeptide

chains called as referred to as protein subunits.

The quaternary structure refers to how these protein subunits

interact with each other and arrange themselves to form a larger aggregate protein complex. The final shape of the protein complex is once again stabilized by various

interactions, including hydrogen-bonding,

disulfide-bridges and salt bridges.

Tuesday, May 2, 2023 19Pranabjyoti Das

Formation of Polypeptide Chain

Polypeptide chain consists of a bunch of different amino acids linked together.

One after another, the amino acids are linked together with each other by Peptide bond.

Between 2 Amino Acids a Monopeptide , between 3 Amino Acids a Dipeptide and so on

When many Amino Acids are held together, it form the Polypeptide chain

Function of ProteinsFunctions of proteins

can be interchangeable with functions of

polypeptides

Type of Protein

Function

Structural Proteins

Support

Storage Proteins

Storage of AA

Transport Proteins

Transport substances

Hormonal Proteins

Coordination

Receptor Proteins

Response to stimuli

Contractile Movement

Defensive Proteins

Disease protection

Enzymatic Proteins

Catalytic action


What are the importance of proteins ?They have a structural function and serve as cell membrane protein, cytoskeleton protein, connective tissue proteins etc

They have an enzymatic function to catalyze biochemical reactions

They carry out a transportation function to carry oxygen in our body

They provide us immunity in the form of Antibody

They help us in our movement by contractile function of muscles

Protein is a body building food for us

And many more…


Questions For You1. What unit are proteins composed of ?

2. How many amino acids are known to form proteins?

3. What is the bond between two amino acids called ?

4. What is the primary structure of a protein ?

5. What are Non-essential Amino Acids ?

6. Who coined the term Protein ?

7. What is a polypeptide chain ?

Protein as a Biomolecule

Education

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