Key difference - substrate level phosphorylation vs. oxidative phosphorylation

Substrate-level phosphorylation and oxidative phosphorylation are two types of phosphorylation processes that occur in living organisms. Phosphorylation refers to the transfer of a phosphate group from one compound to another. In general, the term “phosphorylation” is used to describe the formation of ATP . Organisms use energy in the form of ATP. In eukaryotes , the organelle that produces ATP is the mitochondrion . However, some of the ATPs are also produced in the cytoplasm . The main difference between substrate level phosphorylation and oxidative phosphorylation is that substrate level phosphorylation is a direct phosphorylation of ADP with a phosphate group using the energy obtained from a coupled reaction, while oxidative phosphorylation is the production of ATP from the oxidized NADH and FADH is ₂ .

Key areas covered

1. What is phosphorylation at substrate level - definition, process, properties 2. What is oxidative phosphorylation - definition, process, properties 3. What are the similarities between phosphorylation at substrate level and oxidative phosphorylation - overview of the common characteristics 4. What is the Difference Between Substrate Level Phosphorylation and Oxidative Phosphorylation - Key Differences Comparison

Key Terms: adenosine diphosphate (ADP), adenosine triphosphate (ATP), cytoplasm, glycolysis, Krebs cycle, mitochondria, oxidative phosphorylation, phosphorylation at substrate level

What is phosphorylation at the substrate level?

Substrate-level phosphorylation refers to a type of phosphorylation in which a phosphate group is transferred from a substrate to ADP. It can also add a phosphate group to guanosine diphosphate (GDP) to form a guanosine triphosphate (GTP). The phosphate group is removed directly from a substrate by a coupled reaction and transferred to ADP or GDP. An example reaction of phosphorylation at the substrate level is shown in Figure 1 .

Figure 1: Phosphorylation at the substrate level

Phosphorylation at the substrate level occurs in glycolysis and in the Krebs cycle . Glycolysis is the first step in both aerobic and anaerobic breathing . In glycolysis, two phosphorylation reactions occur at the substrate level and four ATP molecules are produced. Phosphoglycerate kinase and pyruvate kinase are the two enzymes involved in phosphorylation at the substrate level in glycolysis. The Krebs cycle occurs only in aerobic respiration . In the Krebs cycle, phosphorylation takes place at the substrate level in the mitochondrial matrix. In the Krebs cycle, too, two phosphorylation reactions occur at the substrate level. Phosphoenolpyruvate carboxykinase and succinate CoA ligase are the two enzymes involved in phosphorylation at the substrate level in the Krebs cycle. During the Krebs cycle, 2ATPs are produced by phosphorylation at the substrate level. In addition to ATP, 6NADHs and 2FADH ₂ s are produced, whose reduction potentials are used in the formation of ATP through oxidative phosphorylation during aerobic respiration.

What is Oxidative Phosphorylation?

Oxidative phosphorylation refers to a type of phosphorylation that uses the energy released by the electron transport chain to create ATP. It is found in the inner membrane of the mitochondria in eukaryotes. In prokaryotes, oxidative phosphorylation takes place in the plasma membrane. High-energy molecules such as NADH and FADH ₂ , which are formed in glycolysis, the Krebs cycle and the fatty acid cycle, are reoxidized in the electron transport chain. The energy released by these molecules is used in the formation of ATP in oxidative phosphorylation. Oxidative phosphorylation only takes place during aerobic respiration. It produces 26 ATP per glucose molecule . The oxidative phosphorylation is shown in Figure 2 .

Figure 2: Oxidative phosphorylation

The enzymes involved in oxidative phosphorylation are ATP synthase, cytochrome reductase, cytochrome C oxidase and NADH-Q reductase.

Similarities between substrate level phosphorylation and oxidative phosphorylation

• Both the substrate level and oxidative phosphorylation add a phosphate group to the ADP.
• Enzymes are involved both at the substrate level and in oxidative phosphorylation.
• Both substrate level and oxidative phosphorylation can occur in the mitochondria.

Difference between phosphorylation at the substrate level and oxidative phosphorylation

definition

Phosphorylation on the substrate plane: The phosphorylation at substrate level refers to a type of phosphorylation, is transmitted in which a phosphate group from one substrate to ADP.

Oxidative phosphorylation: Oxidative phosphorylation refers to a type of phosphorylation that uses the energy released by the electron transport chain to create ATP.

Location

Phosphorylation at substrate level : Phosphorylation at substrate level takes place in the cytoplasm and in the mitochondrial matrix.

Oxidative phosphorylation: Oxidative phosphorylation takes place on the inner membrane of the mitochondria.

mechanism

Phosphorylation at the substrate level: A phosphate group is removed directly from a substrate by a coupled reaction and transferred to ADP.

Oxidative phosphorylation: Phosphate groups are added from the energy released in the electron transport chain.

correlation

Phosphorylation at the substrate level : Substrate phosphorylation is a direct phosphorylation.

Oxidative phosphorylation: Oxidative phosphorylation is an indirect phosphorylation.

Appear

Phosphorylation at substrate level : Phosphorylation at substrate level takes place in glycolysis and in the Krebs cycle.

Oxidative phosphorylation: Oxidative phosphorylation takes place in the electron transport chain.

Oxidation / reduction of coenzymes

Phosphorylation at the substrate level: NAD and FAD are reduced during phosphorylation at the substrate level.

Oxidative phosphorylation: NADH ⁺ and FADH ⁺ are oxidized during oxidative phosphorylation.

Net ATP production

Phosphorylation at the substrate level: Four ATPs are produced during phosphorylation at the substrate level.

Oxidative phosphorylation: 34 ATPs are produced during oxidative phosphorylation.

Redox potential

Phosphorylation at the substrate level: The change in the redox potential of the substrate is less during phosphorylation at the substrate level.

Oxidative phosphorylation: The change in the redox potential of the substrate is more likely to occur during oxidative phosphorylation.

Degree of oxidation

Phosphorylation at the substrate level: During phosphorylation at the substrate level, partial oxidation of the substrate occurs.

Oxidative phosphorylation: In oxidative phosphorylation, the electron donors are completely oxidized.

diploma

Substrate-level phosphorylation and oxidative phosphorylation are two methods of producing ATP in living organisms. ATP is the main form of energy molecules used in cellular mechanisms. Phosphorylation at the substrate level occurs in glycolysis and in the Krebs cycle. Oxidative phosphorylation takes place in the electron transport chain. Substrate-level phosphorylation is a direct type of phosphorylation in which a phosphate group is transferred directly to an ADP molecule. Oxidative phosphorylation is an indirect method of phosphorylation in which the energy released in the electron transport chain is used to generate ATP. The main difference between substrate-level phosphorylation and oxidative phosphorylation lies in the mechanisms by which ATP is produced.

Reference:

1. “Substrate-level phosphorylation.” Wikipedia, Wikimedia Foundation, October 6, 2017, available here .2.Berg, Jeremy M. “Oxidative Phosphorylation”. Biochemistry. 5th Edition, US National Library of Medicine, Jan. 1, 1970, available here .

Image courtesy:

1. “Substrate-level phosphorylation to generate ATP” By Yikrazuul - Own work (Public Domain) via Commons Wikimedia 2. “Mitochondrial electron transport chain - Etc4” By Fvasconcellos 22:35, September 9, 2007 (UTC) - vector version by w : Image: Etc4.png by TimVickers, (Public Domain) via Commons Wikimedia