Kulsoom
Structure & Classification
of Proteins
Dr. Bibi Kulsoom
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Kulsoom
Proteins
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Proteins: Amino Acids
Peptide bond
One Amino acid structure
Protein molecule
Hydrolysis by
digestive enzymes
Amino acids
http://www.hardbodysuccessblog.com/.a/6a00e00995147488330115704e4379970c-pi
http://www.whitetigernaturalmedicine.com/wp-content/uploads/2012/02/amino-acid-structure.jpg
Hydrocarbon chain
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Proteins are Composed :
of 20 Amino Acids
Essential amino acids
Non-Essential amino acids
1. Arginine (partially essential)
1. Alanine
2. Histidine
2. Aspartic acid
3. Isoleucine
3. Asparagine
4. Leucine
4. Cysteine
5. Lysine
5. Glutamic acid
6. Methinine
6. Glutamine
7. Phenylalanine
7. Glycine
8. Threonine
8. Proline
9. Tryptophan
9. Serine
10. Valine
10. Tyrosine
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Proteins & their Classification
Classification is based on
• Composition
• Shape
• Function
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Classification Based on Composition
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Simple proteins:
A protein that contains amino acids only.
Examples: albumin, globulins & histones.
2.
Conjugated Proteins:
A protein that have some non-protein moiety in its structure along
with protein part.
3.
Derived proteins:
Proteins derived from simple and conjugated proteins by physical
or chemical treatment. Examples: peptones peptides and
denatured proteins.
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Conjugated Proteins
Nucleoproteins
Glycoproteins
Mucoproteins
Lipoproteins
Phosphoproteins
Chromoproteins
Metalloproteins
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Nucleoproteins
Proteins examples:
Histones, telomerase.
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Glycoproteins
Proteins examples:
Glycoproteins of cell membrane, Follicle-stimulating hormone
(FSH), Luteinizing hormone (LH).
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http://designanduniverse.com/articles/images/cell/cell_membrane.jpg
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Lipoproteins
Proteins examples:
Low density lipoprotein (LDL), high density lipoprotein (HDL).
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http://www.scientificpsychic.com/health/lipoproteins-LDL-HDL.html
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Phosphoproteins
Proteins examples:
Enzymes (protein in nature) are phosphorylated temporarily for their regulation.
P
Inactive
Active
P
Active
Inactive
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Chromoproteins
Proteins examples:
Hemoglobin, cytochromes (enzymes).
Cytochromes P450
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http://chemistry.wiki.elanco.net/file/view/hemoglobin.jpg/120238735/hemoglobin.jpg
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Metalloproteins
Proteins examples:
Hemoglobin, Ceruloplasmin (protein that stores and
transports copper)
Ceruloplasmin
Ceruloplasmin
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Based on Shape
Proteins
Globular Proteins
Fibrous Proteins or Scleroproteins
Albumin
Collagens
Globulins
Elastins
Glutelins
Keratins
Prolamines
Histones
Globins
Protamines
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Globular Proteins
Hemoglobin and myoglobin are examples of globular proteins.
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Fibrous Proteins or Scleroproteins
Collagen, keratin and elastin are examples of fibrous proteins.
-keratin
Collagen fiber
-keratin
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Classification based on Function
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Structural Proteins
Proteins
gives
our
cells
shape,
strength as well as enable movements.
Proteins examples:
keratin, collagen, elastin.
Structure Examples:
Hair,
wool,
nails,
horns,
hoofs, tendons, cartilage.
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Contractile Proteins
Proteins examples:
Actin & myosin
Location in body:
Contracting fibers in muscle.
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Transport Proteins
Protein examples:
• hemoglobin (Carries oxygen
in blood)
•
serum albumin (Carries fatty
acids in blood)
Storage Proteins
Proteins examples:
• Different for different sustances.
• Ferritin (Stores iron in spleen)
• legumes and beans in plants
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Proteins as Enzymes
• Many proteins act as biological
catalysts or enzymes.
• Thousands of different enzymes
exist in the body.
• Examples: catalase, amylase,
trypsin, lipase.
Immunological Proteins
Proteins examples:
Gamma globulins
• when a pathogen enters the
Antibody
body, the immune system
produces antibodies against it
that fight against the invader.
Antibody
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http://www.microbiologyonline.org.uk/about-microbiology/microbes-and-the-human-body
http://www.biology.arizona.edu/immunology/tutorials/antibody/graphics/antibody.gif
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Proteins as Buffers
Example:
Plasma proteins and intracellular
preoteins.
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http://human-physiology---ashley-vg.wikispaces.com/Chemical+Aspects+of+Physiology
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Maintaining Osmotic Pressure
Protein examples:
 Albumin, globin, globulin.
Protein as Hormone
Hormone
Examples: Insulin, glucagon,
growth hormone etc.
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http://www.hcc.bcu.ac.uk
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Protein Channels & Receptors
Channels: Protein pores that run like tunnels across the lipid bilayer will allow
specific materials that we need, like glucose, to slip through the membrane.
Receptors: proteins that mediate the effects of hormones in side the cell.
Cell cytoskeleton
Examples: Microfilaments, intermediate filaments & microtubules.
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Clotting Factors
Clotting proteins
activate and make
meshwork of fibrin to
stop bleeding.
Examples:
Factors I, II, III, IV, V
etc.
http://www.buzzle.com/img/articleImages/323361-36236-16.jpg
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Type of protein
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Example
Function
Structural proteins
keratin, collagen
Hair, wool, nails, horns, hoofs,
tendons, cartilage
Contractile proteins
actin, myosin
Contracting fibers in muscle
Transport proteins
hemoglobin
serum albumin
Carries oxygen in blood
Carries fatty acids in blood
ferritin
Stores iron in spleen
Hormones
insulin, glucagon
Regulates use of blood sugar
Immunological
proteins
antibodies
Rid the body of foreign proteins
amylase
Promotes the break down of starch to
the simple sugar glucose.
neurotoxin
Cobra venom blocker of nerve
functions
Storage proteins
Enzymes
Toxins
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