Enzymes And Respiratory: 9 Facts You Should Know

Enzymes and Respiratory these two are very related terms.An enzyme involved in the processes of cellular respiration, such as an oxidase, dehydrogenase, or catalase. The mitochondria are known to house the cell’s respiratory enzymes, which play a crucial role in many essential functions.

All of the four stages of cellular respiration, with the exception of glycolysis, which takes place in the cytoplasm outside of the mitochondria, occur in the mitochondria. The Krebs cycle enzymes and Respiratory are found in the mitochondrial matrix, whereas the oxidative phosphorylation enzymes are found in the inner mitochondrial membrane.

Does respiration use enzymes?

Cellular respiratory enzymes receive information about the condition of the cell’s energy from the molecules that bind them. Examples of molecules that control the enzymes involved in cellular respiration include ATP, ADP, and NADH.

For example, large levels of ATP signal that the cell has enough ATP and does not need to produce any more through cellular respiration. In this instance, a product “feeds back” to block its pathway, which is a form of feedback inhibition.

How are enzymes involved in respiration?

Enzymes’ primary function in the respiratory reaction is to help move electrons from one molecule to another. These transfers are known as “redox” reactions, where the oxidation of one substance (the loss of an electron) must be accompanied by the addition of an electron to another (reduction).

The cytoplasm, or fluid, of the cell is where the respiration reaction’s initial phase is carried out. Nine distinct chemical processes, each mediated by a different enzyme, make up glycolysis.

Dehydrogenase, an enzyme, and NAD+, a coenzyme (non-protein aid), are the main participants in glycolysis. By stealing two electrons from glucose and transferring them to NAD+, dehydrogenase oxidises glucose. During the process, glucose “splits” into two pyruvate molecules, which carry on the reaction.

Roles of enzymes in respiratory?

Enzymes’ key contribution to the respiratory reaction is their help in transporting electrons from one molecule to another. These exchanges are known as “redox” reactions because they require that the oxidation of one substance (the loss of an electron) and the addition of an electron to another (the addition of an electron) occur simultaneously (reduction).

Enzymes reduce the quantity required. Reactions can occur at lower temperatures thanks to enzymes. Since each reaction in a cell requires a particular enzyme, those enzymes are known as substrates. created during a reaction when an enzyme and a substrate come into contact.

Proteins called enzymes assist our bodies’ chemical reactions move forward more quickly. For several processes, including digestion and liver function, enzymes are crucial. Health issues might result from having too much or too little of a specific enzyme. Healthcare professionals can also use the enzymes in our blood to look for injuries and illnesses.

How are enzymes used in respiratory?

An individual enzyme is responsible for catalysing each step in cellular respiration because each enzyme has a different substrate-binding site. The specificity of the enzymes helps to ensure that the right reaction in the process is occurring at the right moment.

Glycolysis is the mechanism that unites aerobic and anaerobic respiration. One molecule of glucose is converted into two molecules of pyruvic acid during the process of glycolysis, which takes place in the cytoplasm. Neither carbon dioxide nor oxygen are used during glycolysis. In mitochondria, pyruvic acid is further metabolised. The mitochondrial matrix and inner mitochondrial membrane are home to respiratory enzymes that are invWhere are enzymes used in Respiratory.

Where are enzymes used in respiratory?

Multiple proteins are incorporated in the two membrane envelope that surrounds the mitochondria. The mitochondrial matrix, which is located inside these membranes, houses some of the enzymes necessary for cellular respiration.

The mitochondria are found in almost all eukaryotic cells. A cell may have just one mitochondria, but more frequently, hundreds or thousands. The quantity normally varies with the cell’s metabolic activity. Multiple proteins are incorporated in the two membrane envelope that surrounds the mitochondria. The mitochondrial matrix, which is located inside these membranes, houses some of the enzymes necessary for cellular respiration. On the inner membrane are several enzymes, including the one that produces ATP. Cellular respiration can take place in an efficient manner because to this arrangement.

Plant respiratory enzyme examples?

The two primary categories of respiration enzymes are highlighted in the paragraphs that follow. Among them are: 1. Non-Oxidative 2.0 Oxidative.



These enzymes facilitate the exchange of carbon atoms within the same molecule or the transfer of phosphate groups from one type of molecule to another. Some of these enzymes require the presence of magnesium ions to function.


Aldolase, for example, divides fructose 1,6-bisphosphate into 3-phosphoglyce-raldehyde and dihydroxyacetone phosphate. Other enzymes catalyse hydrolysis-free processes in which carbon chains are broken.


They operate as catalysts in processes that remove CO2 from a molecule. Pyruvic carboxylase and oxaloacetic acid carboxylase are the enzymes that catalyse the decarboxylation of pyruvic acid and oxaloacetic acid, respectively.


These enzymes do not divide the molecules; instead, they catalyse the addition or removal of water from the molecules. Enolase takes H20 from 2-phospoglyceric acid to form 2-phosphoenolpyruvic acid, one of the reversible processes of glycolysis. Fumarase and isoaconitase are enzymes that catalyse the reversible conversion of L-malic acid to fumaric acid and aconitic acid to isocitric acid, respectively.



By moving hydrogen atoms and electrons from one type of molecule to another, these enzymes generate intracellular oxidation and reduction. Some of them are similar to oxidases in activity since they can transfer hydrogen directly to air’s oxygen. Others can function in anaerobic or aerobic environments and transfer hydrogen and electrons to molecules other than O2.

Anaerobic or “aerobic” dehydrogenases exist. The majority of plant dehydrogenases belong to the latter group. Dehydrogenases function on two substrates simultaneously, one of which is oxidised (dehydrogenated), while the other is reduced (hydrogenated).

Both the former and the latter are referred to as hydrogen and electron donors and acceptors, respectively. The substrate that serves as the hydrogen donor is the source of these enzymes’ names. Coenzymes that act as hydrogen and electron acceptors are present in the majority of dehydrogenases.

Diphosphopyridine nucleotide (DPN) and triphosphopyridine nucleotide are two examples of such coenzymes (TPN). Both the former and the latter go by the names NAD (nicotinamide adenine dinucleotide) and NADP, respectively (nicotinamide adenine dinucleotide phosphate). The hydrogen is then transferred by the reduced coenzymes to the FADH2-derived flavin adenine dinucleotide (FAD).


Cytochromes move electrons from FADH2 to atmospheric oxygen. A water molecule is created when oxygen combines with hydrogen ions and electrons.


They help the electrons go from the substrate to the molecule of oxygen. H2O2 is created as a result as the final product. They can only function in aerobic environments. Cytochrome oxidase, phenolase, and ascorbic acid oxidase are the three main oxidases that are known to exist in plants. These enzymes catalyse the last stage of the Krebs cycle , where oxygen is the reactant and water (H2O) is the end product.


When hydrogen peroxide or organic peroxides produced in plant cells are present, this set of enzymes causes the oxidation of phenolic compounds like pyrogallol and catechol. So, rather than oxygen, hydrogen peroxide acts as the hydrogen acceptor.


This enzyme is found in all living things, and because it is present in cells, it inhibits the buildup of H2O3, which can happen as a byproduct of metabolism.

Animal respiratory enzyme examples?

All organisms go through the metabolic process of breathing. It is a biological process that takes place inside of an organism’s cells. The breakdown of glucose in this process results in the production of energy (ATP-Adenosine triphosphate), which is then utilised by cells to carry out numerous tasks. Respiration is a function of all living things, from simple single-celled creatures to dominant multicellular ones.


It is the Key enzymes in redox reactions. It is this enzymes that transfer electrons, hydrogen or oxygen from one molecule to another. 


Decarboxylase are enzyme that catalyses the reaction to remove carbon dioxide from a molecule. E.g. in anaerobic respiration-


These are enzyme that removes hydrogen from a molecule. e.g. such as found during Kreb’s cycle.The activity of this enzyme can be measured using an artificial hydrogen acceptor such as TTC (triphenyl tetrazolium chloride – which turns pink!)

Enzymes and Respiratory
Dehydrogenase from Wikipedia

Fungi respiratory enzyme examples?

Animals use a linear respiratory chain with massive respiratory complexes to transport electrons from NADH to molecular oxygen. The majority of fungus, however, use branched respiratory chains. Fungi usually follows the aerobic mode of respiration but anaerobic fungi have also been found in fresh water lakes, landfill sites, deep-sea sediments and rumen of herbivores.

Aerobic respiratory enzymes

Aerobic cellular respiration is cellular respiration that requires oxygen. There are three main steps to this process: glycolysis, the citric acid cycle, and oxidative phosphorylation.

Respiratory enzymes of Glycolysis:

  • Hexokinase,
  • Phosphofructokinase
  • Pyruvate kinase.

Respiratory enzymes of citric acid cycle:

  • Citrate synthase
  • Aconitase
  • Isocitrate dehydrogenase
  • Alpha-ketoglutarate dehydrogenase
  • Succinyl-CoA synthetase
  • Succinate dehydrogenase
  • Fumarase
  • Malate dehydrogenase

Respiratory enzymes of oxidative phosphorylation.

  • NADH-coenzyme Q oxidoreductase (complex I)
  • Succinate-Q oxidoreductase (complex II)
  • Electron transfer flavoprotein-Q oxidoreductase.
  • Q-cytochrome c oxidoreductase (complex III)
  • Cytochrome c oxidase (complex IV)
  • Alternative reductases and oxidases
  • Organization of complexes.

Anaerobic respiratory enzymes

  • Pyruvate decarboxylase
  • Pyruvate dehydrogenase
  • Alcohol dehydrogenase

Bacteria respiratory enzyme examples?

The bacterial cell’s mesosome has infoldings and is similar to eukaryotic cells in that it increases the surface area available for respiration. As a result, it forms and is a key component of the energy source used by cells to function. Mesosomes are a few types of cell wall invasions. Mesosomes are found in bacteria’s primordial cells.

  • Lactate dehydrogenase (LDH).
  • Catalase
  • Superoxide dismutase
  • Peroxidase enzymes


The respiratory enzymes of the cell are known to be located in the mitochondria and are of fundamental importance in vital processes.Examples are decarboxylases, which remove carboxyl groups as carbon dioxide, and dehydrases, which remove a molecule of water. The reverse reactions are catalyzed by the same enzymes.

Sadiqua Noor

I'm a recent post graduate in biotechnology, my area of interest is molecular biology and genetics, apart from these i have keen interest in scientific article writing in simpler words so that the people from non science background can also understand the beauty and gifts of science. I had 5 years experience as a tutor.

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