includes structure of proteins, types of proteins ,properties of proteins ,can use as a quick resource for presenting a seminar

1. PROTEINS
K. Siva sai Priya
Msc 1st year
Dept of botany
Srikrishnadevaraya university
PROTEINS

2. INTRODUCTION
• Proteins are unbranched polymers constructed from standard
alpha aminoacids
• These are the most complex of biological molecule.
• These are the most abundant organic molecules of living system.
• Proteins occupy 50 per weight of every cell.
• Some proteins function as enzymes to carry out biochemical
reactions neccesory for maintaining and building life.

3. STRUCTURE OF PROTEINS
• Structure of protein is related to its molecular size ,relative
proportions of various amino acids ,their sequence and
arrangement of peptide chains in three dimensional shapes
• The number of amino acids in protein may range from two
to several thousand
• Protein shape is determined by the sequence of amino acids
• The peptide bond allow the rotation of protein

4. CLASIFICATION OF
PROTEINS
PRIMARY
STRUCTURE
SECONDARY
STRUCTURE
TERITARY
STRUCTURE
QUARTENERY
STRUCTURE

5. Primary structure
The primary structure is related to its
aminoacid sequence .
The amino acids are linked to each
other by peptide bonds.
Each polypeptide sequence has its own
unique sequence of amino acids.
Amino acids are linked with one
another through peptide bonds.

6. SECONDARY STRUCTURE
Secondary structure refers to spatial
arrangement of main chain atoms
These are stabilised by hydrogen bonds
between the carbonyl oxygen and amide
hydrogen in polypeptide back bone
Peptide chains may acquire spiral shape
or may be in zig zag shape.

7. ALPHA HELIX
It is rigid rod like structure that forms polypeptide
chain when twits into helical confirmation
Right handed helices are more favorable because
of less steric clash and stabilised by intrachain
hydrogen bond
In alpha chain helix there are 3.6 amino acid
residues per turn of helix
A single turn involves 13 atoms from O to H of
hydrogen bonding so it is referred as 3.6(13)
helix.

8. BETA (ß) PLEATED SHEET
Beta pleated sheets are formed when two or more polypeptide
chain segments line side by side each segment referred to beta
pleated sheets
The distance between them is approximately 3.5 ang
These are stabilised by interchain hydrogen bonding.
The beta sheets may be parallel and antiparallel .The anti parallel
strands are more stable than parallel beta sheet
These have their own Φ and Ψ values associated with respect to
the co group

9. • Term Tertiary refers to unique three dimensional confirmation
• Twisting and folding of polypeptide chain represents the
teritary structure
• Covalent and non covalent interactions stabilize the teritary
structure
TERITARY
STRUCTURE
• Quaternary refers to four
• It is the arrangement of multiple folded protein or coiling
protein molecules
• Some of proteins consists of 2 or more polypeptide chains
which may called oligomers .these sub units may be identical
or non identical
QUARTENARY
STRUCTURE

11. CLASSIFICATION BASED ON COMPOSITION
SIMPLE
PROTEINS
• Simple proteins are those which on hydrolysis give only amino acids and
no other major organic or inorganic products
• Examples egg(Albumin),Blood (globulin),Glutelins ,Histones ,sclero
proteins
CONJUGATED
PROTEINS
• Consists of a simple protein combined with non protein component
• Non protein part called prosthetic group
• These are classified based on prosthetic group
• Eg :Glycoproteins ,lipoproteins, metalloproteins ,phosphoproteins

12. DERIVED PROTEINS
• These are derived from simple and
conjugated proteins
• Eg : proteans,proteases ,peptones
,peptides

13. CLASSIFICATION BASED ON
SHAPE AND SOLUBILITY
FIBROUS PROTEINS
GLOBULAR PROTEINS

14. FIBROUS PROTEINS
• These are rod shaped molecules that are insoluble in water and physically
tough
• These have structural and protective functions
• They can be stretched and contracted like thread
• These proteins consist of largely secondary structure
• Eg: keratin ,collagen ,fibrogen etc.

15. GLOBULAR PROTEINS
• These are compact spherical molecules that are water soluble
proteins
• These have several types of seconday structures
• The main driving force for folding water soluble globular protein is
to pack hydrophobic side interior and hydrophillic toward outside

17. CLASSIFICATION BASED
ON BIOLOGICAL
FUNCTION.
ENZYMES
TRANSPORT
PROTEINS
STORAGE
PROTEINS

18. ENZYMES
• These are the proteins which
are specialised in their
function with catalytic activity
• These regulate most of
biological reactions in inside
living cells
TRANSPORT PROTEINS
• These are proteins help in
transportation of nutrients
and vital gases
• These carry essential
substances throughout body
eg:haemoglobin
STORAGE PROTEINS
• These are the proteins stored
inside the cells or tissues as
reserve food and can be
mobilized at the time of
requirement
• Eg :casein

19. CONTRACTILE PROTEINS
• These proteins have a ability to
contract and to change the shape
• These include Actin and Myosin
• Present in form of filamentous
protein in muscle cells
STRUCTURAL PROTEINS
• These are the major component
of tendons cartilages and bones
• These are fibrous proteins named
collagen ,keratin and fibrin
• These support cell shape and
movement

20. PROPERTIES OF PROTEINS

21. PHYSICAL PROPERTIES
Contains
carbon
,hydrogen
,oxygen
,nitrogen,and
small amount
of sulphur
Composed of
amino acids
linked
together by
peptide
bonds
Proteins act
as catalysts
,enzymes at
speed up the
rate of
chemical
reaction
Provide
structural
shape and
support to
cells
Transports
substances
across cell
membrane

22. CHEMICAL PROPERTIES
DENATURATION OF PROTEINS
• Denaturation is the process in which
protein loose their native confirmation .It
include the loose of quartenery ,territory
,and secondary structures
• It include the breaking of non covalent and
covalent bonds and also loose the
biological activity
• Eg of denaturating agents may be strong
acids and bases,organic solvents
,detergents ,heat etc .

23. IMPORTANCE OF PROTEINS
Proteins play an important role in formation of proto plasm
Nucleoproteins are complex proteins and act as carrier of heredity materials from one
generation to other generation
Enzymes are the biological catalyst and also called proteins
Gelatin is obtained by heating bones skin and tendons in water .it is used in bakery
goods
Casein is another protein used in manufacturing industry
Proteins obtained from soya bean used as plastics

24. THANKYOU