Amino acids and it's function

1. AMINO ACIDS
Dr. S.ANEES
PROFESSOR & HEAD
DEPT.OF BIOCHEMISTRY
DCMS, HYD

2. AMINO ACIDS WITH ALIPHATIC
SIDE CHAINS:
 1. GLYCINE
 2. ALANINE
 3.VALINE
 4. LEUCINE BRANCHED CHAIN
 5. ISOLEUCINE AMINOACIDS

3. WITH SIDE CHAINS CONTAINING
HYDROXYLIC(OH) GROUPS
 6. SERINE
 7. THREONINE

4. WITH SIDE CHAINS CONTAINING
SULPHUR ATOMS
 8. CYSTEINE
 9. METHIONINE

5. WITH SIDE CHAINS CONTAINING
ACIDIC GROUPS OR THEIR AMIDES
 10. ASPARTIC ACID
 11. ASPARAGINE
 12. GLUTAMIC ACID
 13. GLUTAMINE

6. WITH SIDE CHAINS CONTAINING
BASIC GROUPS
 14. ARGININE
 15. LYSINE
 16. HISTIDINE

7. CONTAINING AROMATIC RINGS
 17. PHENYLALANINE
 18.TYROSINE
 19. TRYPTOPHAN

8. IMINO ACIDS
 1. PROLINE
 NO FREE AMINO - NH (IMINO –GRP)
GROUP COO-
SIDE CHAIN FORMS
A RING

9. CLASSIFICATION OF AMINO ACIDS BASED ON
THEIR RELATIVE HYDROPHILICITY &
HYDROPHOBICITY
 HYDROPHOBIC:
1. ALANINE
2. VALINE
3. LEUCINE
4. ISOLEUCINE
5. PHENYLALANINE
6. TYROSINE
7. TRYOTOPHAN
8. METHIONINE
9. PROLINE

10. HYDROPHILIC
 10. ARGININE
 11. HISTIDINE
 12. LYSINE
 13. GLUTAMICACID
 14. GLUTAMINE
 15. ASPARTIC ACID
 16. ASPARAGINE
 17. GLYCINE
 18. SERINE
 19. THREONINE
 20. CYSTEINE

11. CLASSIFICATION OF AMINO ACIDS ACCORDING TO
NUTRITIONAL REQUIREMENTS:
 NUTRITIONALLY ESSENTIAL:
 1.P--- PHENYLALANINE
 2.V---VALINE
 3.H--- HISTIDINE
 4.I --- ISOLEUCINE
 5. L--- LEUCINE
 6.T---TRYPTOPHAN
 7. M--- METHIONINE
 8. A--- ARGININE
 9. L--- LYSINE
 10.T---THREONINE

12. NUTRITIONALLY NONESSENTIAL
 11. GLYCINE
 12. ALANINE
 13.SERINE
 14. CYSTEINE
 15.TYROSINE
 16. ASPARTICACID
 17. ASPARAGINE
 18. GLUTAMICACID
 19. GLUTAMINE
 20. PROLINE

13. CLASSIFICATION OF AMINO ACIDS BASED ON
THEIR FATE OF CARBON SKELETONS
 GLYCOGENIC AND KETOGENIC :
 1. PHENYLALANINE
 2.TYROSINE
 3.TRYPTOPHAN
 4. LYSINE
 5. ISOLEUCINE

14. KETOGENIC:
 LEUCINE

15. PROPERTIES OF AMINO ACIDS
 GLYCINE--- SMALLEST
 GETS ACCOMODATED IN
OTHERWISE INACCESSIBLE REGIONS OF
PROTEIN STRUCTURE
 HYDROPHOBIC AMINO ACIDS GET
ACCOMODATED IN INTERIOR OF CYTOSOLIC
PROTEINS.
 CHARGED ‘R’ GROUPS OF POLAR AMINO
ACIDS - FORM SALT BONDS OF PROTEIN
STRUCTURE.

16. PROPERTIES CONTD.
 -OH OF SERINE AND -SH OF CYSTEINE
HELP IN ENZYME CATALYSIS.
 AMINO ACIDS HELP IN ACID BASE
BALANCE DUE TO THEIR IONIZABLE
WEAK ACIDIC AND BASIC GROUPS.

17. ZWITTERIONS
 AMINO ACIDS ARE AMPHOTERIC
MOLECULES --- CONTAIN BOTH POSITIVE &
NEGATIVE CHARGES WHICH ARE AFFECTED
BY THE Ph of THE SURROUNDING MEDIUM.
 THEY HAVE AT LEAST 2 IONIZABLE WEAK
ACID GROUPS (PROTON DONORS ) ---COOH
AND ---NH3+ AND THEIR CONJUGATE
BASES ( PROTON ACCEPTORS) -- --COO-
AND NH2.

18.  AT PHYSIOLOGICAL Ph BLOOD PLASMA
7.4 CARBOXYL GROUPS MAINLY EXIST
AS CARBOXYLATE IONS R—COO-.
 AMINO GROUPS AS R-NH3+.
 MOLECULAR SPECIES LIKE THESE WITH
EQUAL NUMBER OF POSITIVEAND
NEGATIVE CHARGESARE CALLED
ZWITTERIONS.
THE Ph at which the molecule exists as
Zwitterion is - Isoelectric pH.

19. PEPTIDE BOND
 CONDENSATION REACTION
 INVOLVES REMOVAL OF ONE MOL. OF
WATER BETWEEN THE ALPHA AMINO
GROUP OF ONE AMINO ACIDAND ALPHA
CARBOXYL GROUP OF THE SECOND
AMINO ACID.
 AMIDE LINKAGE
 REQUIRES ENERGY IN THE FORM OF ATP.

20. PEPTIDE BOND
 H
 NH3+---C—COOH
 I H
 CH3 + NH2---C---COO-
 I
 H2O R
 H H
 NH3+----C---C----NH----C---COO-
 I II I
 CH3 O R


21. PEPTIDE BOND IS PRESENT IN TRANS
CONFIGURATION
 H H
 I I
 NH3----- C N
 1.32 COO-
 R C C
 R
 O H

22. CHARACTERISTICS OF PEPTIDE BOND
 ALMOST ALL PEPTIDE BONDS ARE TRANS
IN CONFIGURATION.
 THE 2 ALPHA CARBON ATOMS ARE ON
THE OPPOSITE SIDES OF PEPTIDE BOND.
 IT IS PLANAR WITH NO FREEDOM OF
ROTATION ABOUT THE BOND THAT
CONNECTS THE C AND N ATOMS.

23. CHARACTERISTICS OF PEPTIDE BOND
 THIS SEMIRIGIDITY HAS IMPORTANT
CONSEQUENCES FOR ORDERS OF PROTEIN
STRUCTURE ABOVE THE PRIMARY LEVEL.
 PEPTIDE BOND HAS A PARTIAL DOUBLE
 BOND CHARACTER.
 C—N DISTANCE -- 1-32A
 SINGLE BOND --- 1.49A
 DOUBLE BOND --- 1.27 A

24. .
 PEPTIDE BOND IS UNCHARGED WHICH
ALLOWS POLYMERS OF AMINO ACIDS TO
FORM TIGHTLY PACKED GLOBULAR
STRUCTURES.

25. .
 TRIPEPTIDE
 CYSTEINE ALANINE GLYCINE
 SH
 I
 CH2 H CH3 H H
 I I I I I
 NH3---C-----C-----N----C---C----N----C—COO-
 I II I II I
 H O H O H

26. BIOLOGICALLY IMPORTANT
PEPTIDES
 INSULIN : CONSISTS OF 2 POLYPEPTIDE
CHAINS ; 30 AND 21 AMINO ACIDS.
 GLUCAGON: 29 AMINO ACIDS
 ACTH : 39 AMINO ACIDS
 OXYTOCIN: 9 AMINO ACIDS

27. BIOLOGICALLY IMPORTANT
PEPTIDES
 BRADYKININ: 9 AMINO ACIDS. INHIBITS
INFLAMMATION OF TISSUES.
 THYROTROPIN RELEASING HORMONE: TRH
3 AMINO ACIDS.
 BETA LIPOTROPIN
 BETA MSH
 ENCEPHALINS
 ENDORPHINS

28. BIOLOGICALLY IMPORTANT PEPTIDES
 AMANITIN:
 ANTIBIOTICS: -VALINOMYCIN
- GRAMICIDIN
 ANTITUMOUR AGENT :
 BLEOMYCIN

29. BIOLOGICALLY IMPORTANT PEPTIDES
 ASPARTAME: COMMERCIALLY
SYNTHESIZED
 L- ASPARTYL PHENYLALANYL METHYL
ESTER
 CYANOBACTERIA TOXINS: MICROCYSTINS
AND NODULARINS
CAUSE HEPATIC TUMOURS

30. BIOLOGICALLY IMPORTANT PEPTIDES
 GLUTATHIONE:
 GAMMA GLUTAMYL CYSTEINYL
GLYCINE.
 2GSH  REDUCED GLUTATHIONE
 GSSG- OXIDISED GLUTATHIONE

31. STRUCTURE OF GLUTATHIONE
 SH
 I
 O CH2 H
 II I I
 C C N
CH2 N C CH2
I I II I
CH2 H O COO-
I
H-- C—NH3 GAMMA GLUTAMYL CYSTEINYL
I GLYCINE
COO-

32. PRIMARY STRUCTURE OF PROTEIN
 Primary Structure of the Polypeptide chain
is the order in which Amino Acids are joined
together and it includes the location of any
Disulfide bonds.
 It shows the number, structure and order of
all the amino acid residues in a polypeptide
chain.

33. SECONDARY STRUCTURE
 IT IS THE REGULAR , RECURRING
ARRANGEMENTS IN SPACE OF ADJACENT
AMINO ACID RESIDUES IN A
POLYPEPTIDE CHAIN.

34. FORCES/BONDS THAT STABILIZE THE SECONDARY
STRUCTURE OF PROTEIN
1. HYDROGEN BONDS:
- POLAR ‘R’ GROUPS PRESENT ON THE
SURFACE OF PROTEINS FORM HYDROGEN
BONDS WITH WATER MOLECULES.
- AMINOACYL RESIDUES OF THE
BACKBONE FORM HYDROGEN BONDS
WITH ONE ANOTHER.

35. HYDROPHOBIC INTERACTIONS
 HYDROPHOBIC INTERACTIONS INVOLVE
NONPOLAR ‘R’ GROUPS OF AMINOACYL
RESIDUES.
 IN POLAR SOLUTION LIKE WATER
HYDRPHOBIC ARE CONCENTRATED IN THE
INTERIOR OF THE PROTEIN.
 IN NONPOLAR ENVIRONMENT , NONPOLAR
‘R’ GROUPS PARTICIPATE IN HYDROPHOBIC
INTERACTIONS WITH ALKYL SIDE CHAINS OF
FATTY ACYL ESTERS OF MEMBRANE
BILAYERS.

36. ELECTROSTATIC INTERACTIONS
 ELECTROSTATIC INTERACTIONS OR SALT
BONDS ARE FORMED BETWEEN OPPOSITELY
CHARGED GROUPS LIKE AMINO TERMINAL
OR CARBOXYL TERMINAL GROUPS OF
PEPTIDES AND THE CHARGED ‘R’ GROUPS
OF POLAR AMINOACYL RESIDUES.

37. VAN DER WAALS INTERACTIONS
 Van derWaals forces are weak and act
over extremely short distances and include
both an attractive & repulsive component.
 The distance at which the attractive force
is maximal and repulsive force is minimal
is - VAN DERWAALS CONTACT
DISTANCE

38. ALPHA HELIX
 BACK BONE OF THE POLYPEPTIDE CHAIN
IS TWISTED ABOUT EACH ALPHA
CARBON ATOM BY EQUAL AMOUNTS TO
FORM A COIL OR HELIX.
 THEY ARE EITHER RIGHT OR LEFT
HANDED. RIGHT HANDED MORE
COMMON.

39. .
 NUMBER OF RESIDUES PER TURN= 3.6.
 AMINOACYL RESIDUES ARE DIRECTED
OUTWARD FROM THE HELIX MINIMIZING
MUTUAL STERIC HINDERANCE.
 H- BONDS STABILIZE ALPHA HELIX.
PEPTIDE NITROGENS  DONORS OF H.
 CARBONYL OXYGEN OF THE 4TH RESIDUE
IN LINE BEHIND  HYDROGEN
ACCEPTOR

40. .
 TIGHTLY PACKED ATOMS AT THE CORE
OF AN ALPHA HELIX ARE VAN DER
WAALS CONTACT WITH ONE ANOTHER.
 ALPHA HELICES SEEN IN:
1. HEMOGLOBIN
2. PLASMA LIPOPROTEINS
3. POLYPEPTIDE HORMONES

41. STRUCTURE OF ALPHA HELIX

42. .

43. BETA PLEATED SHEETS
 SECOND REGULAR STRUCTURE
DESCRIBED.
 ALPHA CARBONS AND THEIR
ASSOCIATED ‘R’ GROUPS ALTERNATE
BETWEEN SLIGHTLY ABOVE AND BELOW
THE MAIN CHAIN OF THE POLYPEPTIDE.
 STABILIZED BY MAXIMUM NUMBER OF
HYDROGEN BONDS.

44. .
 POLYPEPTIDES ALIGNED ALONGSIDE ONE
ANOTHER ARE STABILIZED BY HYDROGEN
BONDS FORMED BETWEEN PEPTIDE
NITROGEN HYDROGENS AND CARBONYL
OXYGENS OF ADJACENT STRANDS.
 UNLIKE THE COMPACT STRUCTURE OF
ALPHA HELIX , PEPTIDE BACKBONES OF
BETA SHEETS ARE FULLY EXTENDED.
 THEY ARE PARALLEL OR ANTIPARALLEL.

45. BETA SHEET

46. BETA SHEET

47. BETA SHEET

48. BETA PLEATED SHEETS
 FOUND IN BOTH FIBROUS AND
GLOBULAR PROTEINS.
 TWISTED BETA PLEATED SHEET FIBRILS
( AMYLOID PROTEIN) ARE DEPOSITED IN
BRAINS OF ALZHEIMER PATIENTS.

49. LOOP REGIONS
 LOOP OR COIL CONFORMATIONS ARE
IRREGULARLY ORDERED.
 FORM MAJOR SURFACE FEATURES OF
PROTEINS.
 EXPOSED TO SOLVENT , RICH IN
CHARGED AND POLAR RESIDUES.
 THEY CONNECT ADJACENT
ANTIPARALLEL BETA SHEETS.

50. LOOP REGIONS
 THEY FORM SITE FOR LIGAND
INTERACTIONS.
 LOOP REGIONS FORM ANTIGEN BINDING
SITES OF ANTIBODIES.

51. BETA TURN OR BETA BEND
 THEY CONNECT TWO ADJACENT STRANDS
OF ANTIPARALLEL BETA SHEETS.
 CONSIST OF 4 AMINO ACIDS AND MAKE A
180 DEGREE TURN.
 FIRST AMINO ACID IS HYDROGEN BONDED
TO FOURTH.
 CONTAIN GLYCINE AND PROLINE.
 OCCUR PRIMARILY AT PROTEIN SURFACES

53. SUPER SECONDARY MOTIFS
 SEEN MOSTLY IN GLOBULAR PROTEINS.
 SMALL SUBUNITS OF SECONDARY
STRUCTURAL ELEMENTS.
 Eg.
1. BETA –ALPHA –BETA 2 STRANDS OF
BETA SHEET CONNECTED BY AN ALPHA
HELIX.
2. GREEK KEY MOTIF.

54. SUPER SECONDARY MOTIFS
 BETA – ALPHA –BETA MOTIF:

55. GREEK KEY MOTIF

56. TERTIARY STRUCTURE
 TERTIARY STRUCTURE REFERSTO
SPATIAL RELATIONSHIPS BETWEEN
SECONDARY STRUCTURAL ELEMENTS.
 SECONDARY & SUPERSECONDARY
STRUCTURES OF LARGE PROTEINS GET
ORGANIZED AS DOMAINS ( COMPACT
UNITS) CONNECTED BY THE
POLYPEPTIDE BACKBONE.

57. TERTIARY STRUCTURE
 PROTEIN FOLDING IN FORMATION OF
TERTIARY STRUCTURE BRINGS
TOGETHER AMINO ACIDS WHICH ARE
FAR APART INTHE PRIMARY STRUCTURE.
 DOMAINS PERFORM DISCRETE
FUNCTIONS:
Eg: BINDING SPECIFIC LIGANDS

58. TERTIARY STRUCTURE
 STABILIZED BY:
1. DISULPHIDE BONDS
2. HYDROGEN BONDS
3. HYDROPHOBIC INTERACTIONS
4. IONIC INTERACTIONS

59. TERTIARY STRUCTURE: DIHYDROFOLATE REDUCTASE

60. QUARTERNARY
STRUCTURE
 PROTEINS WITH 2 OR MORE
POLYPEPTIDE CHAINS ASSOCIATED
BY NON COVALENT FORCES EXHIBIT
QUARTERNARY STRUCTURE.
 THESE ARE MULTIMERIC PROTEINS
AND THE INDIVIDUAL POLYPEPTIDE
CHAINS ARE TERMED PROTOMERS
OR SUBUNITS.
 ADJACENT SUBUNITS ARE LINKED
BY HYDROGEN BONDS AND
ELECTROSTATIC BONDS.

61. QUARTERNARY
STRUCTURE
 2 SUBUNITS  DIMERIC
 4 SUBUNITS TETRAMERIC etc.
 HOMO-OLIGMERIC PROTEINS: IDENTICAL
SUBUNITS
 HETERO-OLIGOMERIC PROTEINS:
 DISSIMILAR SUBUNITS , EACH
PERFORMING A DIFFERENT FUNCTION.
 Eg: ONE SUBUNIT  CATALYTIC ROLE
 ANOTHER SUBUNIT LIGAND
RECOGNITION OR A REGULATORY
ROLE.

62. QUARTERNARY
STRUCTURE
 SUBUNITS MAY FUNCTION
INDEPENDENTLY ‘OR’
 WORK COOPERATIVELY EG:
HEMOGLOBIN

64. DETERMINATION OF PRIMARY STRUCTURE OF PROTEIN
 PURIFICATION OF THE PROTEIN
 ( MANY MOLECULES OF THE SAME PROTEIN ARE TAKEN )
 DETERMINE THE NUMBER OF AMINO ACIDS
 MULTIMERIC PROTEIN SMALL SINGLE
PEPTIDE ( < 100 AMINO -
( ACIDS)
BREAK INTO ITS SUBUNITS
PUT IN
SEQUENATOR
LARGE PEPTIDES SMALL PEPTIDES WITH EDMAN’S
REAGENT
( > 100 PEPTIDES ) ( < 100 PEPTIDES) TO DETERMINE
SEQUENCE
DIGEST WITH SPECIFIC ENZ. SEQUENCE
TO FORM OVERLAPPING
PEPTIDES
SEQUENCE

65. PURIFICATION OF
PEPTIDES
 PRIOR TO DETERMINATION OF
PROTEIN STRUCTURE, PROTEINS
ARE PURIFIED BY :
1. ULTRACENTRIFUGATION
2. POLYACRYLAMIDE GEL
ELECTROPHORESIS.

66. DETERMINATION OF THE NUMBER
OF AMINO ACIDS
1. PEPTIDE BONDS ARE BROKEN
BY
ACID HYDROLYSIS WITH 6N HCL
AT 110DEGREES CENTIGRADE.
2. AMINO ACIDS SEPARATED BY:
3. HPLC OR
4. ION EXCHANGE
CHROMATOGRAPHY.

67. SINGLE SMALL PEPTIDE OF
LESS THAN 100 AMINO ACIDS.
1. PUT IN SEQUENATOR TO DETERMINE
SEQUENCE.
2. SANGER’S REAGENT ( 1-FLOURO 2,4
DINITROBENZENE) OR
3. EDMAN’S REAGENT ( PHENYL
ISOTHIOCYANATE ) CAN BE USED.
BOTH REAGENTS CLEAVE AMINO
ACIDS ONE BY ONE FROM AMINO
TERMINAL END.

68. .
 SEPARATED AMINO ACIDS ARE
IDENTIFIED BY
CHROMATOGRAPHY AND BY USING
NINHYDRIN REAGENT.

69. MULTIMERIC PROTEIN
 BREAK INTO PEPTIDE CHAINS USING
:
1. UREA HYDROLYSES ‘H’
BONDS
2. GUANIDINE HCL & NONCOVALENT
BONDS
1. REDUCING AGENTS ( BREAK
DISULPHIDE BONDS).

70. .
 MULTIMERIC PROTEINS:
MULTIMERIC
PROTEIN
LARGE
PEPTIDES >100
AMINO ACIDS
OVERLAP
PEPTIDES
AND THEN
SEQUENCE
SMALL
PEPTIDES < 100
AMINO ACIDS
SEQUENCE

71. BREAKING DOWN OF LARGE PEPTIDES INTO
SMALLER FRAGMENTS SO THAT THEY CAN BE
SEQUENCED.
 REAGENTS USED FOR ABOVE
PURPOSE:
1. CYANOGEN BROMIDE: CLEAVES ON
–COOH SIDE OF METHIONINE.
2. TRYPSIN: CLEAVES ON THE –COOH
SIDE OF LYSINE & ARGININE
3. O-IODOSOBENZNENE
4. HYDROXYLAMINE
5. MILD ACID HYDROLYSIS

72. OVER LAPPING
PEPTIDES
 PRODUCED BY MULTIPLE
DIGESTS.
 HELPS TO DETERMINE THE
CORRECT SEQUENCE OF THE
DIGESTED SMALL PEPTIDES.

73. OVER LAPPING PEPTIDES
 A B
 C

74. CLASSIFICATION OF
PROTEINS
 1. CLASSIFICATION BASED ON
FUNCTION:
 A. CATALYTIC PROTEINS,
 B. STRUCTURAL PROTEINS - COLLAGEN
 C. CONTRACTILE PROTEINS
 D. TRANSPORT PROTEINS
 E. REGULATORY PROTEINS –
HORMONES
 F. PROTECTIVE PROTEINS

75. CLASSIFICATION BASED ON
COMPOSITION & SOLUBILITY
 1. SIMPLE
 2. CONJUGATED &
 3. DERIVED

76. SIMPLE PROTEINS
 1. ALBUMIN
 2. GLOBULINS
 3. SCLEROPROTEINS
 4. LECTINS
 5. PROTAMINES
 6. PROLAMINES

77. CONJUGATED PROTEINS
 PROTEIN + NON PROTEIN PROSTHETIC
GRP.
 1. GLYCOPROTEINS,
Eg. BLOOD GROUP ANTIGENS,
2. LIPOPROTEINS ,
3. NUCLEOPROTEINS, --- HISTONES

78. .
 4. CHROMOPROTEINS,---- Hb ,
RIBOFLAVIN
 5. PHOSPHOPROTEINS --- CASEIN OF
MILK
 6. METALLOPROTEINS ----
HEMOGLOBIN, CYTOCHROMES ,
CARBONIC ANHYDRASE

79. DERIVED PROTEINS
 THEY ARE DEGRADATION
PRODUCTS OF NATIVE PROTEINS
.
 Eg. PEPTONES

80. CLASSIFICATION BASED ON
SHAPE
 1. GLOBULAR PROTEINS :
 Eg. a. ALBUMIN

b.GLOBULINS

c.HEMOGLOBIN
 2. FIBROUS PROTEINS : Eg. COLLAGEN
 ELASTIN
 FIBRINOGEN

81. CLASSIFICATION BASED ON
NUTRITIONAL VALUE
 1. NUTRITIONALLY RICH PROTEINS :
 COMPLETE PROTEINS
 CONTAIN ALL ESSENTIAL
 AMINO ACIDS
 EG. CASEIN OF MILK,
 EGG ALBUMIN

82. INCOMPLETE PROTEINS
 THEY LACK ONE ESSENTIAL AMINO
ACID
 Eg. PULSES DEFICIENT IN METHIONINE
 CEREALS LACK LYSINE
 ( MUTUAL SUPPLEMENTATION )

83. POOR PROTEINS
 THEY LACK MANY ESSENTIAL
AMINO ACIDS.
 Eg. CORN LACKS TRYPTOPHAN
AND LYSINE.

84. STRUCTURE OF
COLLAGEN
 COLLAGEN TYPE 1 : SKIN & BONE
 TYPE II : CARTILAGE
STRUCTURE:
 POLYPEPTIDE CHAINS.
 EACH CHAIN IS TWISTED INTO A
LEFT HANDED HELIX OF 3
RESIDUES PER TURN,

85. STRUCTURE OF COLLAGEN:
 3 OF THESE ALPHA CHAINS ARE
THEN WOUND INTO A RIGHT
HANDED SUPER HELIX FORMING A
ROD LIKE STRUCTURE 1.4nm IN
DIAMETER & 300nm LONG.
 GLYCINE RESIDUES ARE
PRESENT AT EVERY 3RD POSITION
OF THE TRIPLE HELIX.

86. .
 THE RECURRING AMINO ACIDS
ARE REPRESENTED AS (GLY-X-Y)n.
 X & Y CAN BE ANY OTHER AMINO
ACIDS .
 ABOUT (100/1000) OF X POSITIONS
ARE PROLINE
 ABOUT ( 100/1000) OF Y
POSITIONS ARE LYSINE.

87. .
 COLLAGEN UNDERGOES POST
TRANSLATIONAL MODIFICATION.
 HYDROXYLATION OF PROLINE AND
LYSINE RESIDUES , TO CONFER
RIGIDITY ON THE COLLAGEN
MOLECULE.

89. STRUCTURE OF
MYOGLOBIN
 COMPACT, ROUGHLY SPHERICAL
GLOBULAR PROTEIN.
 Surface is polar and interior is nonpolar.
 EXCEPTION: 2 HISTIDINE Residues
are in centre & help in binding of oxygen
molecule.
 MOLECULAR WT.: 17,000 Daltons
 153 Aminoacyl residues

90. STRUCTURE OF MYOGLOBIN
 75% of amino acid residues are
present in EIGHT RIGHT
HANDED ALPHA Helices.
 Each helix contains 7-20
Aminoacids.
 Myoglobin stores Oxygen with
the help of its prosthetic group
 haeme.

91. STRUCTURE OF MYOGLOBIN

93. STRUCTURE OF HAEMOGLOBIN
 Hemoglobin is a tetrameric
structure.
 Composed of pairs of 2 different
polypeptide
chains .
1. Alpha chain : 141 aminoacyl
residues
2. Beta chain : 146 amino acyl
residues

94. STRUCTURE OF HEMOGLOBIN
 Tetrameric Structures of common
hemoglobins:
 Hb A: alpha2; beta2
 Hb F : alpha 2 ; gamma2
 HbS : alpha 2; S2
 Hb A2( minor adult hemoglobin) :
alpha2 ; delta 2.

96. STRUCTURE OF HEMOGLOBIN SHOWING THE BINDING
OF OXYGEN TO HEME TETRAPYRROLE

97. STRUCTURE OF HEMOGLOBIN

98. PLASMA PROTEINS
 Proteins of the plasma are a complex
mixture containing :
 Simple proteins
 Conjugated proteins ( eg. Glycoproteins)
 Concentration of Total Protein in plasma:
6.5g/dl -- 7.5g/dl.

99. Plasma Proteins

100. FUNCTIONS OF PLASMA PROTEINS
ANTIPROTEASES 1. ALPHA
ANTITRYPSIN,
2. ALPHA 1
MACROGLOBULIN
BLOOD CLOTTING VARIOUS
COAGULATION
FACTORS,
FIBRINOGEN
IMMUNE DEFENSE IMMUNOGLOBULINS,
COMPLEMENT
PROTEINS,

101. FUNCTIONS OF PLASMA PROTEINS
INVOLVEMENT IN
INFLAMMATORY
RESPONSES
C-REACTIVE
PROTEIN
ONCO FETAL ALPHA 1
FETOPROTEIN
TRANSPORT OR
BINDING PROTEINS
1. ALBUMIN– Binds
bilirubin, fatty
acids, steroids etc.
2. Caeruloplasmin
3. Thyroid binding
globulin
4. Transferrin

102. ALBUMIN:
 Major protein of human plasma.
 3.4 –4.7g/dl
 Liver produces 12g of Albumin/day.
 Consists of a single polypeptide
chain of 585 Amino acids &
contains 17 disulfide bonds.
 Molecular Weight: 69kDa.

103. Functions of Albumin:
1. Maintains osmotic pressure
2. Binds to various ligands like ;
 Free Fatty Acids
 Calcium
 Bilirubin
 Steroid Hormones
 Drugs ; Sulphonamides, penicillin,
Aspirin.

104. ALPHA 1 ANTITRYPSIN
 ALPHA 1 ANTITRYPSIN is also
called alpha 1 antiproteinase.
 Single polypeptide chain
containing 3 Oligosaccharide
chains.
 Synthesized by hepatocytes.
 Inhibits trypsin , elastase.

105. CLINICAL SIGNIFICANCE:
 ROLE IN EMPHYSEMA:
ALPHA 1 ANTITRYPSIN prevents
proteolytic damage of lung.
Its deficiency causes EMPHYSEMA.
 ROLE IN LIVER DISEASE:
Its deficiency causes damage to
hepatocytes and Cirrhosis of liver.

106. ALPHA 2 MACROGLOBULIN
 Large plasma glycoprotein
 Mol Wt. –720 kDa
 Forms 8-10% of Total Plasma Protein
 Transports 10% of Zinc in the Plasma.
SITE OF SYNTHESIS:
 Liver
 Monocytes
 Astrocytes

107. FUNCTION OF ALPHA 2
MACROGLOBULIN:
Major member of C3 and C4
group of Complement Proteins.
It is a PANPROTEINASE
inhibitor.

108. HAPTOGLOBIN—alpha2
 Glycoprotein
 Binds Extra corpuscular Hemoglobin.
Hb + Haptoglobin- Catabolized by liver,
(65kDa) (90kDa) Iron is reused.
 Prevents loss of free Hemoglobin into the
kidney.

109. CERULOPLASMIN---ALPHA 2
GLOBULIN
 BINDS 90% OF COPPER PRESENT IN THE
PLASMA.
 EACH MOLECULE BINDS 6 ATOMS OF
COPPER.
 LOW LEVELS OF CERULOPLASMIN ARE
SEEN IN WILSON’S DISEASE.

110. TRANSFERRIN ---BETA 1 GLOBULIN
1. IT IS A GLYCOPROTEIN SYNTHESIZED IN
THE LIVER .
2. IT TRANSPORTS IRON FROM GUT TO
BONE MARROW & OTHER ORGANS.
3. ONE MOLE OF TRANSFERRIN BINDS
TWO MOL OF FE3+. ( FERRIC IRON).

111. IMMUNOGLOBULINS
1) CIRCULATING , HUMORAL ANTIBODIES
SYNTHESIZED BY THE PLASMA CELLS
WHICH ARE SPECIALIZED CELLS OF
‘B’ CELL LINEAGE.
2) SYNTHESIZED IN RESPONSE TO
EXPOSURE TO ANTIGENS.

112. STRUCTURE OF IMMUNOGLOBULIN:
AMINO TERMINAL END OF
BOTH L & H CHAINS
CARBOXYL TERMINAL END OF
LIGHT CHAINS
DISULPHIDE BONDS
CARBOXYL TERMINAL END
OF H CHAINS

113. STRUCTURE OF IMMUNOGLOBULIN

114. STRUCTURE OF IMMUNOGLOBULIN

115. STRUCTURE OF
IMMUNOGLOBULIN

116. STRUCTURE OF IMMUNOGLOBULIN

117. STRUCTURE OF IMMUNOGLOBULIN

118. STRUCTURE OF IMMUNOGLOBULIN
a. IMMUNOGLOBULINS ARE
GLYCOPROTEINS CONSISTING OF TWO
IDENTICAL LIGHT CHAINS &
TWO IDENTICAL HEAVY CHAINS HELD
TOGETHER AS A TETRAMER (L2H2), BY
DISULFIDE BONDS.
b. IT IS Y SHAPED.

119. STRUCTURE OF IMMUNOGLOBULIN
i. LIGHT CHAINS:
MOL.WT.: 23 kDa
HALF OF THE LIGHT (L) CHAIN
TOWARDS THE CARBOXYL TERMINAL
IS  CONSTANT REGION ( CL).
ii. AMINO TERMINAL HALF IS REFERED
TO AS THE VARIABLE REGION (VL).

120. LIGHT CHAIN :
a) ALL LIGHT CHAINS ARE EITHER KAPPA
(k) OR LAMBDA , BASED ON
STRUCTURAL DIFFERENCES IN THEIR
CONSTANT REGIONS.
b) THE VARIABLE (VL) REGIONS FORM
ANTIGEN BINDING SITE ALONG WITH
VARIABLE REGIONS OF HEAVY CHAINS.

121. HEAVY CHAINS:
a) MOLWT: 53-75kDa
b) ONE QUARTER OF HEAVY CHAIN
TOWARDS AMINO TERMINAL IS
VARIABLE REGION.
c) THE REMAINING 3 QUARTERS
TOWARDS CARBOXYL TERMINAL END
IS THE CONSTANT REGION DIVIDED
INTO CH1, CH2, CH3.

122. HEAVY CHAINS:
 HINGE REGION :
THE REGION BETWEEN CH1 & CH2 .
IT CONFERS FLEXIBILITY TO
IMMUNOGLOBULIN HELPING THEM TO
BIND TO ANTIGENIC SITES.

123. .
 THE ANTIGEN BINDING SITE IS FORMED
BY THE VARIABLE REGIONS OF BOTH
HEAVY & LIGHT CHAINS.,
 & IS SPECIFIC FOR A PARTICULAR
ANTIGEN.

124. FIVE TYPES OF HEAVY CHAIN DETERMINE
THE IMMUNOGLIBULIN CLASS.
 FIVE DIFFERENT TYPES OF ‘H’ CHAINS
ARE SEEN BASED ON DIFFERENCES IN
THEIR ‘CH’ REGIONS.
 IgG: H CHAIN IS GAMMA
 IgA: H CHAIN IS ALPHA
 IgM:
 Ig D: H CHAIN IS DELTA
 Ig E : H CHAIN IS EPSILON

125. .
 MONOMER
 IgA(DIMER)
 IgM -
 (PENTAMER)

126. STRUCTURE OF PENTAMERIC
IMMUNOGLOBULIN IgM:

127. IMMUNOGLOBULIN G:
 MAIN ANTIBODY IN SECONDARY
RESPONSE.
 OPSONIZES BACTERIA
 FIXES COMPLEMENT
 NEUTRALIZES BACTERIAL TOXINS &
VIRUSES.
 CROSSES THE PLACENTA.

128. IMMUNOGLOBULIN A
1. SECRETORY ANTIBODY
1. PREVENTS ATTACHMENT OF BACTERIA
& VIRUSES TO MUCOUS MEMBRANES.
2. DOES NOT FIX COMPLEMENT.

129. IMMUNOGLOBULIN M:
 PRODUCED IN PRIMARY RESPONSE TO
AN ANTIGEN.
 FIXES COMPLIMENT
 DOES NOT CROSS PLACENTA

130. IMMUNOGLOBULIN E:
 MEDIATES IMMEDIATE
HYPERSENSTIVITY REACTIONS.
 DEFENDS AGAINST WORM
INFESTATIONS BY CAUSING RELEASE OF
ENZYMES FROM EOSINOPHILS.
 DOES NOT FIX COMPLEMENT