Hemoglobin Part 1 Flashcards
Volume of Hemoglobin in RBC
approx. 34 g/dL
Molecular Weight of Hemoglobin
64,000 Daltons
Functions of Hemoglobin
- Transports oxygen from lungs to tissues
- Transports carbon dioxide from tissues to
the lungs - Transports of nitric oxide
- Contributes to acid-base balance
is a substance that regulate the vascular
tone and considered a vasodilator
Nitric oxide
How does Hgb contributes to acid-base balance?
- Hgb binds to H+ ions (decrease conc.
of H+ ions) → ↑ pH (alkaline) - Hgb releases H+ ions (increase conc.
of free H+ ions) → ↓ pH (acidic)
Note:
H+ ions concentration is inversely proportional to pH
↑ H+ ions →↓ pH (acidic)
↓H+ ions → ↑ pH (alkaline)
Hemoglobin can be separated in what two components?
- Heme portion
- Globin portion
HEME STRUCTURE contains
Heme/ Ferroprotoporphyrin IX
Heme/Ferroprotoporphyrin IX is consist of
- Consists of: Protoporphyrin IX (ring of
carbon, hydrogen, and nitrogen atoms) +
Ferrous Iron - 1 heme: Ferrous iron combines with 1 O2
molecule
How is methemoglobin formed?
Fe2+ → oxidized to Fe3+ → can’t bind O2
→ Methemoglobin (non-functional; no
oxygen-carrying capacity)
GLOBIN STRUCTURE contains
Globin Chains
Globin/Polypeptide Chain is consists of
2 identical pairs of unlike polypeptide chains
Note:
The four globin chains comprising each
hemoglobin molecule consist of two identical
pairs of unlike polypeptide chains:
- The color (2) pink and (2) blue in the
image is the Globin/Polypeptide Chain - 1 pair: 1 globin (pink) + 1 globin (blue);
both horizontally and vertically - 1 pair: 1 alpha and 1 beta (2 different
polypeptide chains, hence unlike
polypeptide chains - Each pair have similar pair with others,
hence 2 identical pairs
Variation in ____________________________
gives rise to different types of globin
chains | variation in ___________________ gives rise to different types of hemoglobin
amino acid sequence; the combination of two globin chains
1 globin chain is divided into __ helices
(linear & rigid) separated by __
nonhelical segments (flexible)
8 ; 7
is composed of 2 alpha and 2 gamma. It composed of different combination of two globin chains
Hemoglobin F
Alpha (Globin Chain) - Number of Amino Acids
141
Gamma (Globin Chain) - Number of Amino Acids
146
Beta (Globin Chain) - Number of Amino Acids
146
Delta (Globin Chain) - Number of Amino Acids
146
Epsilon (Globin Chain) - Number of Amino Acids
146
Zeta (Globin Chain) - Number of Amino Acids
141
Alpha (Globin Chain) - Chromosome
16
Beta (Globin Chain) - Chromosome
11
Gamma (Globin Chain) - Chromosome
11
Delta (Globin Chain) - Chromosome
11
Epsilon (Globin Chain) - Chromosome
11
Zeta (Globin Chain) - Chromosome
16
Hemoglobin Molecule Primary Structure
amino acid sequence
Hemoglobin Molecule Secondary Structure
chain arrangements in helices and nonhelices
Hemoglobin Molecule Tertiary Structure
arrangement of helices in pretzel-like configuration
is suspended between E & F helices
Heme
The pretzel-like configuration will now form a pocket in order to
accommodate the heme
The amino acids present inside the pocket are _________, while the amino acid outside are ___________.
hydrophobic; hydrophilic
This arrangement of acids in the polypeptide chain will make the hemoglobin as a
whole -water soluble.
The iron inside the heme must be maintained in its _______ state so that the heme will be capable of binding to oxygen
ferrous
Hemoglobin Molecule Quaternary Structure/Tetramer
complete Hgb molecule | spherical/globular | 4 heme groups + 4 globin chains
Summary of Hemoglobin Molecule
- 1 Hgb = 4 heme + 4 globin/polypeptide chains
- 1 heme = 4 Pyrrole Rings + 1 Iron (Fe2+) | 1 Hgb = 4 iron molecules
- 1 heme = 1 Iron (Fe2+) + 1 mole of O2 (1.34 mL) | 1 Hgb= 4 moles of O2
predominant adult hemoglobin
Hb A
small % of Hb A is glycated
HbA1c (4% to 6%)
nonenzymatic binding of various sugars
to the globin chain over the life span of the RBC
Glycation
hemoglobin that contains sugar- bound in its globin chain.
Glycated Hemoglobin
The most characterized of the glycated
hemoglobin is
Hb A1c (4 to 6%)
