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Questions and Answers
Globular hemeproteins have heme as a ______ group.
Globular hemeproteins have heme as a ______ group.
prosthetic
Myoglobin functions as a reservoir for ______.
Myoglobin functions as a reservoir for ______.
oxygen
The structure of myoglobin is primarily composed of ______ helices.
The structure of myoglobin is primarily composed of ______ helices.
alpha
The interior of myoglobin is composed of ______ amino acids.
The interior of myoglobin is composed of ______ amino acids.
One molecule of 2,3-BPG binds to a pocket in the center of the deoxyhemoglobin ______.
One molecule of 2,3-BPG binds to a pocket in the center of the deoxyhemoglobin ______.
Increasing levels of 2,3-BPG decreases the ______ affinity of hemoglobin.
Increasing levels of 2,3-BPG decreases the ______ affinity of hemoglobin.
The T-form of hemoglobin is also known as the taut or ______ form.
The T-form of hemoglobin is also known as the taut or ______ form.
Myoglobin can only carry ______ molecule of oxygen.
Myoglobin can only carry ______ molecule of oxygen.
Polypeptide chains within each dimer of hemoglobin are held together primarily by ______ interactions.
Polypeptide chains within each dimer of hemoglobin are held together primarily by ______ interactions.
Hemoglobin has ______ binding sites, one in each subunit.
Hemoglobin has ______ binding sites, one in each subunit.
Hemoglobin can transport both H+ and ______ from tissues to the lungs.
Hemoglobin can transport both H+ and ______ from tissues to the lungs.
The two dimers in hemoglobin are held together by ______ bonds.
The two dimers in hemoglobin are held together by ______ bonds.
CO2 binding stabilizes the T-form of hemoglobin, causing a decrease in ______ affinity.
CO2 binding stabilizes the T-form of hemoglobin, causing a decrease in ______ affinity.
Vitamin C deficiency can lead to ______, which results in fragile capillaries and excessive bruising.
Vitamin C deficiency can lead to ______, which results in fragile capillaries and excessive bruising.
In collagen, proline at position X is essential for ______ conformation of each a-chain.
In collagen, proline at position X is essential for ______ conformation of each a-chain.
Collagen is the most abundant ______ in the human body.
Collagen is the most abundant ______ in the human body.
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Study Notes
Hemeproteins and Oxygen Transport
- Globular Hemeproteins: Contain heme as a prosthetic group, a non-protein molecule essential for their function.
- Myoglobin: Serves as an oxygen reservoir in muscle tissue.
- Primarily composed of alpha helices, with a nonpolar interior and charged amino acids on the surface.
- Hemoglobin:
- Quaternary structure, composed of 2 alpha and 2 beta chains.
- Has four oxygen binding sites, one in each subunit.
- Exists in two forms: T-form (tense, low oxygen affinity) and R-form (relaxed, high oxygen affinity).
- Each dimer is held together by hydrophobic interactions, while dimers are linked through polar bonds.
- 2,3-BPG binds to a pocket in the deoxyhemoglobin tetramer.
- High 2,3-BPG levels decrease oxygen affinity, facilitating oxygen unloading to tissues.
- CO2 binding stabilizes the T-form (deoxy form) of hemoglobin, decreasing oxygen affinity.
- Transports H+ and CO2 from tissues to the lungs.
- Fetal Hemoglobin (HbF): Has a higher oxygen affinity than adult hemoglobin (HbA), ensuring efficient oxygen transfer from the mother to the fetus.
- HbA1c is a form of hemoglobin glycosylated under physiological conditions, used to monitor diabetes.
- Carbon Monoxide (CO): Highly toxic due to its 220 times higher affinity for hemoglobin than oxygen, leading to reduced oxygen delivery to tissues.
Collagen
- Abundant structural protein in the human body.
- Composed of a repeating sequence: (-Gly-X-Y-Gly-)n, where X and Y are often proline and hydroxyproline/hydroxylysine.
- Proline at position X is crucial for the helical conformation of each alpha-chain.
- Triple-helical structure stabilized by interchain hydrogen bonds, further enhanced by Hyp.
- Vitamin C deficiency can lead to scurvy, affecting collagen production and resulting in fragile capillaries and excessive bruising.
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