DEPARTMENT OF MICROBIOLOGY BARKATULLAH UNIVERSITY BHOPAL

s presented by :- Harishchandra Ahirwar (M.Sc. I Sem.)

STRUCTURE AND PROPERTIES OF PROTEINS

CONTENTS1. Introduction2. History3. Structure

A. PrimaryB. SecondaryC. TertiaryD. Quaternary

4. Properties5. Function6. Summary

INTRODUCTION Protiens are the most abundant organic

molecules of the living system.Proteins are the polymer of Amino Acids. The term protien is generally used for a

polypeptide containing more than 50 amino acids.

They are involved in most of our body’s function.

HISTORYThe term ‘Protein’ is derived from a

Greek Word ‘Proteios’ meaning ‘holding the first place.

Berzelius (swedish chemist) suggested the name Protein.

Mulder (dutch chemist) in 1838 used the term Protein.

STRUCTURE OF PROTEIN

1. Primary structure2. Secondary structure3. Tertiary structure 4. Quaternary structure

Primary Structure of а Protein The primary structure of а protein is the sequence of

amino acids present in its peptide chain. The end with the free H3N+ group is called the N-

terminal end, and the end with the free СОО- group is called the С-terminal end...

PRIMARY STRUCTURE

Secondary structureThe secondary structure of a protein results from hydrogen bonds at regular intervals along the polypeptide backbone.– Typical shapes that

develop from secondary structure are coils (an alpha helix) or folds (beta pleated sheets).

ALPHA HELIX

The alpha helix structure resembles а coiled helical spring, with the coil configuration maintained by hydrogen bonds between N – Н and С= О groups of every fourth amino acid.

 

Alpha Helix

The beta pleated sheet secondary structure involves amino acid chains that are almost completely extended.

 

Beta pleated sheet

• Tertiary structure is determined by a variety of interactions among R groups and the polypeptide backbone.– These interactions include hydrogen bonds ,

ionic bonds hydrophobic and van der waals interactions .

Tertiary structure

TERTIARY STRUCTURE

• Quaternary structure results from the aggregation of two or more polypeptide subunits.–Collagen is a fibrous protein of three

polypeptides that are supercoiled like a rope.• This provides the structural strength for their

role in connective tissue.–Haemoglobin is a globular protein with two

copies of two kinds of polypeptides.

Quaternary structure

PROPERTIES OF PROTEINS1. Solubility:-Protein form colloidal solution instead

of true solutions in water.2. Molecular weight:-Proteins vary in their

molecular weight, dependent on no. of Amino acid residues.

3. Shape:-Wide variation in the protein shape, may be globular (insulin), oval (albumin), fibrous (fibrinogen).

4. Isoelectric pH:-At isoelectric pH, proteins exist as dipolar ions.

5. Acidic & basic proteins6. Precipitation of proteins

FUNCTION OF PROTEINSProteins perform a great variety of specialized and essential function in the living cells

These functions are grouped as Static (Structural) Dynamic

Structural functions :- Certain protiens are primarily responsible for structure and strength of body. These include collagen and elastin found in bone matrix, vascular system and other organs.

Dynamic functions :- The dynamic functions of protiens are as acting like enzymes , hormones, blood clotting factors ,immunoglobins,

REFRENCESBIOCHEMISTRY BY Dr. U. Satyanarayana

TEXTBOOK OF BIOCHEMISTRY BY Jain & Jain

Images from google

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