1. Introduction of protein
2. Structure of protein
3. Types of protein
4. Ramachandran plot of protein
5. Extraction and techniques
Protein Introduction -
Proteins are Nitrogenous macromolecules substances found
in living system. Essential for cell structure and cell functions.
Protein term first suggested, in 1838, by a
Swedish chemist Berzelius.
Macromolecules - Very high molecular
weights, The term macromolecule was
coined by Schaudinger in 1920s.
Protein are polymers of The Amino acids.
In body -
H20 > Proteins > Lipids
> Carbohydrates > Nucleic Acid.
O2 - 60%, C
- 20%, H - 10%, N - 3%,
Ca - 2.5%.
Amino acids -
R = H ---- Glycine amino acid
R
= CH3 ----
Alanine amino acid
R
= CH2OH ----
Serine amino acid.
22 Amino acids discovered in cells.
1. Arginine (R),
2. Histidine (H),
3. Isoleucine (I),
4. Leucine (L),
5. Lysine (K),
6. Methionine (M),
7. Phenylalanine (F),
8. Theonine (T),
9. Tryptophan (W),
10. Valine (V),
11. Alanine (A),
12. Asparagine (N),
13. Aspartic acid (D),
14. Glycine (G),
15. Serine (S),
16. Tyrosine (Y),
17. Glutamic acid (E),
18. Cysteine (C),
19. Glutamine (Q),
20. Proline (P),
21. Selenocysteine (U),
22. Pyrrolysine (O)
New discovered amino acids -
- Selenocysteine (encode by UGA
codon)
- Pyrrolysine (encode by UAG codon).
Amino acids nature -
Acidic amino acids - Aspartic acid (D), Glutamic acid (E).
Basic amino acids - Lysine (K), Arginine (R), Histidin (H), Tryptophan
(W).
Neutral amino acids - Glycine (G), Valine (V), Alanine (A).
Aromatic amino acids - Phenylalanine (F), Tyrosine (Y), Tryptophan (W).
Essential Amino Acids -
Essential Amino Acids cannot synthesized by
de nevo, in organism at a rate commensurate with its demand.
Examples -
Arginine (R), Histidine
(H), Isoleucine (I), Leucine (L), Lysine (K), Methionine (M), Phenylalanine
(F), Theonine (T), Tryptophan (W), Valine (V).
Non essential amino acids -
Non essential Amino Acids synthesized by de
nevo, in organism at a rate commensurate with its demand.
Examples -
Alanine (A), Asparagine (N), Aspartic acid
(D), Glycine (G), Serine (S), Tyrosine (Y). Glutamic acid (E).
Conditional essential -
Cysteine (C), Glutamine (Q), Proline (P).
Primary amine - One Carbon bounded with to
the Nitrogen.
Second amine - Two Carbon bounded with to
the Nitrogen.
Tertiary amine - Three Carbon bounded with
to the Nitrogen.
Protein chain formation - Two amino acid
attached with dipeptide bond.
Protein Molecular weight = Add Amino acids molecular weights - 18 (H20, release).
Protein structure -
Effects of Temperature on protein structure - high temperature least affects primary structure.
Types of proteins -
Simple protein -
1. Fibrous protein. 2. Globular
protein.
Compound protein -
1. Glycoprotein. 2.
Leithoprotein. 3. Phoshpoprotein etc.
Simple Protein -
Made by only amino acids
1. Fibrous protein -
Elongated,
rod like structures, Form by strong hydrogen binding- between intermolecular
strands, some time repeated unit, resistant to enzymatic digestion, Mostly-
Primary & Secondary structures.
Examples - Collagen (Most abundant protein
in animal body),
Elastin,
Keratin (Hardest protein, due to cysteine).
2. Globular protein -
Spherical in
shape, forms colloids with water, dissolve in water. Weak Hydrogen bonding,
Enzymatic functions, mostly primary, secondary, tertiary and Quaternary
structures.
Examples -
Rubisco (Most abundant
protein on Earth / plants),
Albumin,
Globin,
Histone,
Notes - Fibrous proteins and globular
proteins differ in size, shape, solubility, appearance as well as in function.
Compound protein -
Made by
Amino acids and non amino acids parts (Prosthetic part).
Examples -
Phoshpoprotein. - Amino acids + Phosphoric acids
Like - Milk protein (Casein), Pepsin (digestive enzymes secret from stomach's chief cells.
Leithoprotein - Amino acids + Lecithin
Like - Fibrinogen (blood clotting protein)
Glycoprotein - Amino acids + Carbohydrates
Like - LH (Leutinizing Hormone), FSH (Follicular stimulating
factor, Anterior pituitary Hormone).
Antibodies.
Fertilizin (egg surface protein),
Antuferilizing ( sperm surface protein).
Lipoprotein - Amino acids + lipids
Like - plasma membranes
Nucleoprotein
- Amino acids + nucleic acids
Like - DNA+ HISTONE
PROTEIN,
RNA + Protein
Chromoprotein
- Amino acids + Metals
Like - Haemoglobin (Fe),
Cytochrome (Fe).
Ramachandran plot -
Introduced by G. N. Ramachandran, Peptide conformations are defined
by the values of fi and sai.
For L amino acids (mostly found in
eukaryotes, NH2 group presents in left side).
Notes - Glycine ( Much broader range area)
Proline (Greatly restricted area)
For D amino acids ( NH2 group
presents in right side), its are mirror form L amino acids.
"Amino acids encode by Codon (three nucleotides long
unit)"
Isoelectric pH (pl) - Protein's Net electric charge is zero, but
contain positive and negative charge groups. (Zwitterion).
pH below its
pI - +Ve Change (Acidic)
pH above its
pl - - Ve charge (Basic)
Protein extraction and Observation -
Extraction - (in Buffer, solution).
Organ - tissue - cells - Homogenate - lysis
with enzymes, Sonication -
Centrifuge
Use techniques -
Spectrophotometer
( Absorb light at ~280nm )
( Absorbation directly proportional to the
concentration of the solution - The Lambert-Beer Law )
- Chromatography
- Electrophoresis
- Immunoassay
