myoglobin

Examples of myoglobin in the following topics:

• Energy Requirements

  • Heart muscle also contains large amounts of a pigment called myoglobin.
  • Myoglobin is similar to hemoglobin in that it contains a heme group (an oxygen binding site).
  • Myoglobin transfers oxygen from the blood to the muscle cell and stores reserve oxygen for aerobic metabolic function in the muscle cell.
  • The heme component of myoglobin, shown in orange, binds oxygen.
  • Myoglobin provides a back-up store of oxygen to muscle cells.

• Slow-Twitch and Fast-Twitch Muscle Fibers

  • Due to their large oxygen requirements, slow-twitch fibers are associated with large numbers of blood vessels, mitochondria, and high concentrations of myoglobin, an oxygen-binding protein found in the blood that gives muscles their reddish color.
  • As fast-twitch fibers generally do not require oxygenation, they contain fewer blood vessels and mitochondria than slow-twitch fibers and less myoglobin, resulting in a paler colour.

• Aerobic Training vs. Strength Training

  • Type I fibers appear red due to the presence of the oxygen-binding protein myoglobin.
  • They contain large and numerous mitochondria with high levels of myoglobin that gives them a red pigmentation.
  • Type II fibers are white due to the absence of myoglobin and a reliance on glycolytic enzymes.

• Carbon Monoxide Poisoning

  • Additionally, myoglobin and mitochondrial cytochrome oxidase are thought to be adversely affected.
  • For example, carbon monoxide binds to the hemeprotein myoglobin and impairs its ability to utilize oxygen.
  • This results following a recurrence of increased carboxyhemoglobin levels and this effect may be due to a late release of carbon monoxide from myoglobin, which subsequently binds to hemoglobin.

• Homologs, Orthologs, and Paralogs

  • For example, the hemoglobin gene of humans and the myoglobin gene of chimpanzees are paralogs.
  • The genes encoding myoglobin and hemoglobin are considered to be ancient paralogs.

• Biosynthesis of Tetrapyrroles

  • Hemoglobin and myoglobin are two O2-binding proteins that contain iron porphyrins.

• Muscle Fatigue

  • With aging, levels of ATP, CTP, and myoglobin begin to decline, reducing the muscle's ability to function.

• Skeletal Muscle Fibers

  • The sarcoplasm is rich with glycogen and myoglobin, which store the glucose and oxygen required for energy generation, and is almost completely filled with myofibrils, the long fibers composed of myofilaments that facilitate muscle contraction.

• Iron

  • Iron plays an important role in biology, forming complexes with molecular oxygen in hemoglobin and myoglobin.

• Homologous Structures

  • For example, the hemoglobin gene of humans and the myoglobin gene of chimpanzees are considered paralogs.