carbonic anhydrase

Examples of carbonic anhydrase in the following topics:

• Biomolecules

  • A reaction similar to this is almost instantaneous with carbonic anhydrase.
  • The structure of the active site in carbonic anhydrases is well known from a number of crystal structures.
  • The positively charged zinc ion polarizes the coordinated water molecule, and the nucleophilic attack by the negatively charged portion on carbon dioxide proceeds rapidly.
  • The catalytic cycle produces the bicarbonate ion and the hydrogen ion as the equilibrium favors dissociation of carbonic acid at biological pH values.
  • Active site of carbonic anhydrase.

• RBC Physiology

  • Carbon dioxide is associated with blood acidity.
  • RBCs secrete the enzyme carbonic anhydrase, which catalyzes the conversion of carbon dioxide and water to carbonic acid.
  • Carbonic anhydrase also removes water from carbonic acid to turn it back into carbon dioxide and water.
  • This reaction can occur without the presence of RBCs or carbonic anhydrase, but at a much slower rate.
  • With the catalyst activity of carbonic anhydrase, this reaction is one of the fastest in the human body.

• Diuretics

  • Carbonic anhydrase inhibitors inhibit the enzyme carbonic anhydrase which is found in the proximal convoluted tubule.

• Carboxysomes

  • Carboxysomes are intracellular structures that contain enzymes involved in carbon fixation and found in many autotrophic bacteria.
  • It is thought that the high local concentration of the enzymes, along with the fast conversion of bicarbonate to carbon dioxide by carbonic anhydrase, allows faster and more efficient carbon dioxide fixation than is possible inside the cytoplasm.
  • Carboxysomes are bacterial microcompartments that contain enzymes involved in carbon fixation.
  • These compartments are thought to concentrate carbon dioxide to overcome the inefficiency of RuBisCo (ribulose bisphosphate carboxylase/oxygenase) - the predominant enzyme in carbon fixation and the rate limiting enzyme in the Calvin cycle.
  • These organelles are found in all cyanobacteria and many chemotrophic bacteria that fix carbon dioxide.

• Carbon Dioxide Transport

  • Carbon dioxide is carried in the blood through three different ways.
  • This is due to deoxygenated blood's increased capacity to carry carbon dioxide, and from the carbon dioxide loaded from the tissues during tissue gas exchange.
  • This means that carbon dioxide reacts with water to form carbonic acid, which dissociates in solution to form hydrogen ions and bicarbonate ions.
  • Dissolved carbon dioxide is already able to diffuse into the alveolus, while hemoglobin-bound carbon dioxide is unloaded into the plasma.
  • Next, the action of carbonic anhydrase breaks carbonic acid down into carbon dioxide in water, which leaves the cell by diffusion.

• Transport of Carbon Dioxide in the Blood

  • This form transports about 10 percent of the carbon dioxide.
  • Binding of carbon dioxide to hemoglobin is reversible.
  • Carbonic anhydrase (CA) within the red blood cells quickly converts the carbon dioxide into carbonic acid (H2CO3).
  • This produces the carbonic acid intermediate, which is converted back into carbon dioxide through the enzymatic action of CA.
  • While carbon dioxide can readily associate and dissociate from hemoglobin, other molecules, such as carbon monoxide (CO), cannot.

• Anion Regulation

  • Bicarbonate ions result from a chemical reaction that starts with carbon dioxide (CO2) and water - two molecules that are produced at the end of aerobic metabolism.
  • Carbon dioxide is produced in large amounts in tissues that have a high metabolic rate and is converted into bicarbonate in the cytoplasm of red blood cells through the action of an enzyme called carbonic anhydrase.

• The Carbon Cycle

  • Carbon enters the atmosphere in the form of carbon dioxide via the carbon cycle and returns to organic carbon via photosynthesis.
  • Carbon is released as carbon dioxide when a volcano erupts or from volcanic hydrothermal vents.
  • Carbon dioxide reacts with water to form bicarbonate and carbonate ions.
  • Photosynthesis converts carbon dioxide gas to organic carbon, while respiration cycles the organic carbon back into carbon dioxide gas.
  • Volcanic activity and human emissions bring this stored carbon back into the carbon cycle.

• Indoor Pollution: CO and CO2

  • Carbon monoxide and carbon dioxide are products of combustion reactions; in large amounts, carbon monoxide can cause suffocation.
  • Carbon monoxide (CO) and carbon dioxide (CO2) are both colorless, odorless gases.
  • Carbon dioxide is also produced during cellular respiration, when humans turn glucose and oxygen into energy, water, and carbon dioxide.
  • Carbon monoxide is highly toxic.
  • Older cars can also produce carbon monoxide.

• Properties of Carbon

  • Allotropes of carbon are not limited to diamond and graphite, but also include buckyballs (fullerenes), amorphous carbon, glassy carbon, carbon nanofoam, nanotubes, and others.
  • At higher temperatures, carbon will react with oxygen to give carbon oxides, and metals to give metal carbides.
  • Carbon has two stable, naturally occurring isotopes: carbon-12 and carbon-13.
  • Carbon-12 makes 98.93% and carbon-13 forms the remaining 1.07%.
  • Some allotropes of carbon: a) diamond, b) graphite, c) lonsdaleite, d–f) fullerenes (C60, C540, C70); g) amorphous carbon, h) carbon nanotube.