This document provides information about amino acids, protein structure, and hemoglobin. It discusses: 1. The primary, secondary, tertiary, and quaternary levels of protein structure. The alpha helix and beta pleated sheet are described as examples of secondary structure. 2. Specific amino acids like glycine and tryptophan, as well as collagen structure which contains high amounts of glycine. 3. The roles of vitamins like vitamin C in collagen formation and diseases like scurvy that can result from deficiencies. 4. Additional biomolecules like glutathione and albumin, describing their structures, functions, and relationship to diseases. 5. The structure of hemoglobin including

1. For B.Sc Optometry Students
Amino acids / Proteins
Amino acids / Classification of amino acids
Proteins / Structure of amino acids / Collagen
structure / Glutathione / Albumin / Hemoglobin
Basics in transport of gases / Abnormalities

2. Amino Acid – General Structure

3. D and L amino acid

4. Dissociation of Amino acid

5. Titration of Amino acid

6. Protein Structure
1. Primary Structure
2. Secondary Structure
3. Tertiary Structure
4. Quaternary Structure

7. Primary structure
The simplest level of protein structure, primary structure, is simply the
sequence of amino acids in a polypeptide chain

9. Secondary Structure
Alpha helix

10. In an α helix,
1. the carbonyl (C=O) of one amino acid is
hydrogen bonded to the amino H (N-H) of an
amino acid that is four down the chain.
2. the carbonyl of amino acid 1 would form a
hydrogen bond to the N-H of amino acid 5
3. each turn of the helix containing 3.6 amino
acids.
4. R groups of the amino acids stick outward from
the α helix

11. In a β pleated sheet
• two or more segments of a polypeptide chain
line up next to each other, forming a sheet-like
structure held together by hydrogen bonds.
• The hydrogen bonds form between carbonyl
and amino groups of backbone, while the R
groups extend above and below the plane of the
sheet.

14. Tertiary structure

16. Glycine
1. the smallest/Simplest of the
amino acids.
2. Aliphatic and Non-polar
3. Ambivalent, meaning that it can
be inside or outside of the protein
molecule.
4. An aqueous solution at or near
neutral pH, glycine will exist
predominantly as the zwitterion
5. Collagen contains about 35%
glycine in collagen's helix
structure in conjunction
with hydroxyproline
6. inhibitory neurotransmitter in
the central nervous system,
especially in the spinal
cord, brainstem, and retina

17. Why glycine is not optically active?

18. Tryptophan
1. an essential amino acid
2. Aromatic and Non-polar
3. largest of the amino acids
4. a precursor to
the neurotransmitter serotonin
and the hormone melatonin.
5. An antidepressant
6. Anti anxiety
7. Induce sleep

19. Collagen Structure
• polypeptide chain is left handed
• 3 amino acid per turn
• Three alpha chains is twisted
about each other
• super helical twist is right handed

20. Chain 1
Chain 2
Chain 3

21. Collagen Structure

22. • The collagen polypeptides
have a very specific amino
acid composition:
– 1/3 Gly
– 1/4 Pro
– 1/4 Hypro (hydroxyproline)
and 5-Hylys (hydroxylysine)
• These residues follow a strict
sequence where Gly is always
repeated every third position
– WHY??;
13
Collagen Structure

23. • The presence of Gly at every third
residue allows each collagen chains to
form a tightly wound helix that can
accommodate Pro/Hypro (which are
otherwise rarely included in helices);
• Since the helix has 3 a.a. per turn,
having Gly at every third residue means
that Gly is always on the same side of
the helix;
• It just so happens that Gly is always
positioned at the center of the triple
helix;
• This allows close packing of the three
helices, which can interact and yield a
very strong, rope-like structure.
Collagen Structure

24. Procollagen
Tropocollagen
Collagen
Fibril
Collagen
Fiber

25. 25
Collagen, Vitamin C and scurvy
• The formation of Hydroxy proline
requires the enzymatic modification
of Pro in a reaction which involves:
– Prolyl hydroxylase (an enzyme)
– Fe+2
• Ascorbic acid, a derivative of Vit C
and an antioxidant, keeps iron in its
reduced Fe+2 form, and not the
oxidized, more stable Fe+3 form.
• Humans cannot make Vit C on their
own
• In the absence of Vit C, the collagen
triple helix cannot assemble
properly, leading to a much softer
connective tissue.

26. C10H17N3O6S
Structure
1. a tri-peptide
2. a gamma linkage between the
first two amino acids (instead of
alpha linkage)
3. Gamma linkage resists
degradation by intracellular
peptidases.
Glutathione (GSH)

27. Functions
1. Antioxident
2. neutralization of free radicals and reactive oxygen
compounds
3. used in metabolic and biochemical reactions such as DNA
synthesis and repair, protein synthesis, amino acid transport,
and enzyme activation
4. It has a vital function in iron metabolism
Glutathione (GSH)

28. Structure
1. the most abundant plasma
protein in humans
2. A globular protein
3. single polypeptide chain of 585
amino acid
4. 55% α-helix and remaining
45%is the β-structure
5. Liver produces about 12g of
albumin per day
Albumin

29. Functions of Albumin
1. essential for maintaining the
osmotic pressure needed for
proper distribution of body
fluids between intravascular
compartments and body
tissues.
2. colloid osmotic pressure
3. a plasma carrier /transport
protein for
 Thyroid hormones,
 fatty acids,
 Ca2+, Cu2+, K+, Na+
 Hemin
 Vit D
 Drugs
4. Anticoagulant, Antioxident,
Acid base balance in body

30. Serum Albumin Test
1. a simple blood test that
measures the amount of
albumin in blood
2. Normal range of human
serum albumin
• adults - 3.5 to 5 g/dL.
• children - 2.9–5.5 g/dL
Urine albumin test
1. Normal Range in urine
collected for 24 hrs
• Adults at rest: < 80 mg
• Adults moving around: <
150 mg

31. Hypoalbuminemia
• In Blood <3.5 g/dL
• may be indicative
of liver failure
– Cirrhosis
– Hepatitis
• Malnutrition , Burns,
Surgery, acute disease
• Nephrotic syndrome
• Cause edema
Hyperalbuminemia
• In blood 4.9 g/dL
• Dehydration
• Vit A deficiency
• High protein diet
• In urine
– Kidney Damage
– Diabetic kidney damage
– pregnancy

32. Hemoglobin
• Hb is globular protein, four subunits
• There are two types of protein sub-units i.e., α
and β.
• 2 alpha (141 aa) chain and 2 beta (146) chain
• Both alpha and beta chains have 75% alpha
helical structure
• Normal Hb% in adult male is 14 to 16 gm
• Globin is rich in Histidine and lysine

33. Hemoglobin

34. Structure of Hemoglobin
• Fe2+ ferrous has 6 valencies
• Fe is linked to pyrrole ring by 4 co ordinate bonds
• A fifth bond is with histidine

35. Structure of Hemoglobin
showing proximal histidine

36. Oxy and deoxy Hemoglobin
• Hemoglobin exist in two forms
– 1) deoxy form: No oxygen is bound to iron.
Oxygen atom bounds to Fe and forms hydrogen
bond with distal histidine.
– 2) oxy form: dioxygen is bound to iron.
A water molecule is present instead of Oxygen
between Fe and distal histidine

37. Oxy and deoxy Hemoglobin

38. What is partial pressure?
A gas will move from an area where its partial pressure is higher to an area
where its partial pressure is lower.
total pressure
exerted by a
mixture of gases is
the sum of the
partial pressures
of the gases in the
mixture.

39. Transport of gases

40. Transport of gases
Oxygen
• In lungs partial pressure of
O2 is high
• Hb is fully saturated with O2
at lungs
• In tissue partial pressure of
O2 is less
• O2 is released at the tissue
Carbon Dioxide
• In lungs partial pressure of
CO2 is less
• CO2 is released from Hb
• In tissue partial pressure of
CO2 is high
• CO2 is taken by Hb at tissue

41. Transport of CO2
• Transported in mainly three ways
• Dissolved form: Dissolved in plasma (10%)
– CO2 + H2O H2CO3 HCO3
- + H+
• By RBC: CO2 is converted to H2CO3 inside the
RBC (75%)
• As carbamino hemoglobin (15%)
– R-NH2 + CO2 R-NH-COOH

42. Types of Hemoglobin
Type Components Peculiarity
Adult
Hemoglobin
HbA α2 β2
Normal
HbA2 α2 δ2
Normal
Fetal
Hemoglobin
α2 γ2
High affinity
to oxygen
Abnormal β4
Seen in
thalassemia

43. Sickle cell anemia
•Anemia.
Normal RBC -120 days
sickle cells -10 to 20 days
•Episodes of pain.
called crises
a major symptom of sickle cell anemia.
Pain develops when sickle-shaped red
blood cells block blood flow through
tiny blood vessels of chest, abdomen
and joints.
Pain can also occur in bones.
•Painful swelling of hands and feet
•Frequent infections.
•Delayed growth
•Vision problems

44. Thalassemia
1. Alpha thalassemia
2. Beta thalassemia