Protein is a macronutrient that is essential to building muscle mass. It is commonly found in animal products, though is also present in other sources, such as nuts and legumes. Advertisement. There are three macronutrients: protein, fats and carbohydrates. Macronutrients provide calories, or energy.
2. PROTEINS
• The Molecules which yields amino acids upon
hydrolysis are called proteins.
• Proteins are natural polymer of amino acids.
• The number of amino acids in a protein
molecule may range from two to several
thousands.
• Protein molecules contain Nitrogen, Carbon,
Hydrogen and Oxygen.
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3. PROTEINS
• Proteins are the basis for the major structural
components of animal and human tissue.
• They act as biological catalysts (Enzymes),
form structural parts of organisms, participate
in different cell reactions, act as molecules of
immunity and also provide fuel.
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4. SOLUBILIY
•Soluble in water, eg., Albumin,histones etc
•Soluble in 70-80 % alcohol, eg.,Gliadin
•Soluble in dilute salt solution, eg., Globulins,(
serum,milk etc)
•Insoluble protein, eg., Scleroprotein (
collagen,keratin etc)
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5. CLASSIFICATION OF PROTEINS
(a) Simple Proteins
• Those which give one amino acid only upon
hydrolysis.
(b) Conjugated Proteins
• Those which give an amino acid and a non-protein
group upon hydrolysis..
(c) Derived Proteins
• Those which are derived from simple and conjugated
proteins.
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7. STRUCTURE OF PROTEINS
• Depends upon the spatial arrangement of
polypeptide chains.
• Three arrangements are possible.
• Four structures:
i. Primary structure
ii. Secondary structure
iii. Tertiary Structure
iv. Quaternary Structure
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8. The Primary Structure Of Proteins
• The sequence of amino acids in a
polypeptide chain is called a primary
structure.
• Amino Acids are linked with one another
through peptide bonds.
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10. The Secondary Structure Of Proteins
• Peptide chains may acquire spiral shape
or may be present in a zig zig manner.
• This coiling of peptide chains is called the
secondary structure of proteins.
• It is due to Hydrogen bonding.
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12. The Tertiary Structure Of Proteins
• Twisting or folding
of polypeptide
chains represents
tertiary structure of
proteins.
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13. The Quaternary Structure Of Proteins
• Quaternary means four.
• It is the arrangement of multiple folded
protein or coiling protein molecules in a
multi-subunit complex.
• A variety of bonding interactions including
Hydrogen bonding, salt bridges and
disulfide bonds holds the various chains
into a particular geometry.
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16. Denaturation
The process that changes the shape of a protein
molecule without breaking its peptide bonds.
Denaturation breaks the hydrogen bonds that
create the twists and turns of a protein molecule
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17. Properties Of Proteins
• Found in all living organisms.
• Involved in processes such as digestion of
food, cell structure, catalysis, movement,
energy manipulation etc.
• Complex molecules.
• Polymers of amino acids.
• Long chains of amino acids are called
Polypeptides.
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18. Importance of Proteins
• Proteins play an important role in
formation of protoplasm.
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19. Importance of Proteins
• Nucleoproteins are
complex proteins and
act as the carrier of
heredity materials from
one generation to
another.
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20. Importance of Proteins
• Enzymes are the biological catalyst and
they are also proteins
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24. Biuret test – general test for detecting the presence of
peptide bond.
• Named after the compound, biuret
• reagents: cuso4 solution and dilute naoh
• Positive result: formation of pink to violet to blue
color
• principle: complexation of cu+2 with amide N atoms
.
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25. Ninhydrin test – general test for detect ammonia or primary
and secondry amines.
• One of the most sensitive color reactions known
• Reagent/s: ninhydrin (1,2,3 - indanetrione monohydrate) in
ethanol
• positive result: blue to blue violet color
• Principle: oxidative deamination and decarboxylation;
reduction of ninhydrin
• Proline, hydroxyproline, and 2-, 3-, and 4-aminobenzoic acids
fail to give a blue color but produce a yellow color instead
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26. Xanthoproteic test – general test for aromatic amino
acids such as tryptophan, phenylalanine, histidine and
tyrosine.
• Presence of electron donating substituents enhances reaction
rate.
• Reagents: conc. HNO3 and conc. Naoh (neutralize excess acid).
• Positive results: formation of yellow precipitate and after
addition of excess naoh (alkaline), an orange precipitate forms.
• Principle involved: nitration of aromatic rings (i.E. Indole in
tryptophan!) Via electrophilic aromatic substitution.
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27. Sakaguchi test – specific for arginine (guanido
group)
• Reagents:-napthol, naoh and naobr (and urea to
stabilize color and destroy excess obr- anions).
• Positive result: red to red-orange color.
• Principle: base-catalyzed condensation of
napthol with the guanido group of arginine.
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