Hemeproteins and Oxygen Transport Quiz

Globular hemeproteins have heme as a ______ group.

Myoglobin functions as a reservoir for ______.

The structure of myoglobin is primarily composed of ______ helices.

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 ______.

Increasing levels of 2,3-BPG decreases the ______ affinity of hemoglobin.

The T-form of hemoglobin is also known as the taut or ______ form.

Myoglobin can only carry ______ molecule of oxygen.

Polypeptide chains within each dimer of hemoglobin are held together primarily by ______ interactions.

Hemoglobin has ______ binding sites, one in each subunit.

Hemoglobin can transport both H+ and ______ from tissues to the lungs.

The two dimers in hemoglobin are held together by ______ bonds.

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.

In collagen, proline at position X is essential for ______ conformation of each a-chain.

Collagen is the most abundant ______ in the human body.

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.

Test your knowledge on hemeproteins like myoglobin and hemoglobin, their structures, functions, and oxygen transport mechanisms. This quiz covers key concepts such as binding affinities and the effects of various factors on hemoglobin's oxygen transport capabilities.