Key difference - ADP vs. ATP

ATP and ADP are molecules that contain a large amount of stored chemical energy. The adenosine group of ADP and ATP is made up of adenine, although they also contain phosphate groups. Chemically speaking, ATP stands for Adenosine Tri Phosphate and ADP stands for Adenosine Di Phosphate . The third phosphate of ATP is bound to the other two phosphate groups with a very high energy bond, and a large amount of energy is released when this phosphate bond is broken. ADP leads to the removal of the third phosphate group from ATP. This is the main difference between ATP and ADP . However, compared to ATP, the ADP molecule has much less chemical energy because the high-energy bond between the last 2 phosphates has been broken. Based on the molecular structure of ATP and ADP, they have their own ADP. In this article, let's explain the differences between ATP and ADP.

What is adenosine triphosphate (ATP)?

Adenosine triphosphate (ATP) is used by biological organisms as a coenzyme for intracellular chemical energy transfer within cells for metabolism. In other words, it is the most important energy carrier molecule used in living things. ATP is created in biological systems through photophosphorylation, aerobic respiration, and fermentation, which facilitates the accumulation of a phosphate group on an ADP molecule. It consists of adenosine, which is composed of an adenine ring and a ribose sugar, and three phosphate groups, also called triphosphate. ADP biosynthesis as a result of,

1. Glycolysis

Glucose + 2NAD + + 2 Pi + 2 ADP = 2 pyruvate + 2 ATP + 2 NADH + 2 H ₂ O

2. Fermentation

Glucose = 2CH ₃ CH (OH) COOH + 2 ATP

What is adenosine diphosphate (ADP)?

ADP is made up of adenosine, which is made up of an adenine ring and a ribose sugar, as well as two phosphate groups, also known as diphosphate. This is of crucial importance for the flow of energy in biological systems. It is produced as a result of the dephosphorylation of the ATP molecule by enzymes known as ATPases. The breakdown of a phosphate group from ATP leads to the release of energy for metabolic reactions. The IUPAC name of ADP is [(2R, 3S, 4R, 5R) -5- (6-aminopurin-9-yl) -3,4-dihydroxyoxolan-2-yl] methylphosphonohydrogenphosphate. ADP is also known as adenosine 5'-diphosphate.

Difference Between ADP and ATP

ATP and ADP can have significantly different physical and functional properties. These can be divided into the following subgroups,

abbreviation

ATP: adenosine triphosphate

ADP: adenosine diphosphate

Molecular structure

ATP: ATP consists of adenosine (an adenine ring and a ribose sugar) and three phosphate groups (triphosphate).

ADP: ADP consists of adenosine (an adenine ring and a ribose sugar) and two phosphate groups.

Number of phosphate groups

ATP: ATP has three phosphate groups.

ADP: ADP has two phosphate groups.

chemical formula

ATP: Its chemical formula is C ₁₀ H ₁₆ N ₅ O ₁₃ P ₃ .

ADP: Its chemical formula is C ₁₀ H ₁₅ N ₅ O ₁₀ P ₂ .

molar mass

ATP: The molar mass is 507.18 g / mol.

ADP: The molar mass is 427,201 g / mol.

density

ATP: The density of ATP is 1.04 g / cm ^3.

ADP: The density of ADP is 2.49 g / ml.

Energy state of the molecule

ATP: ATP is a high energy molecule compared to ADP.

ADP: ADP is a low energy molecule compared to ATP.

Energy release mechanism

ATP: ATP + H2O → ADP + Pi ΔG˚ = −30.5 kJ / mol (−7.3 kcal / mol)

ADP: ADP + H2O → AMP + PPi

Functions in the biological system

ATP:

• Metabolism in cells
• Amino acid activation
• Synthesis of macromolecules such as DNA, RNA and protein
• Active transport of molecules
• Maintaining the cell structure
• Contribute to cell signaling

ADP:

• Catabolic pathways such as glycolysis, citric acid cycle and oxidative phosphorylation
• Activation of the platelets
• Play a role in the mitochondrial ATP synthase complex

In summary, ATP and ADP molecules are types of "universal energy sources" and the main difference between them is the number of phosphate groups and the energy content. As a result, they can have significantly different physical properties and different biochemical roles in the human body. Both ATP and ADP are involved in important biochemical reactions in the human body and are therefore considered to be vital biological molecules.

References:

Voet D, Voet JG (2004). Biochemistry 1 (3rd ed.). Hoboken, New Jersey .: Wiley. ISBN 978-0-471-19350-0.

Ronnett G, Kim E, Landree L, Tu Y (2005). Fatty acid metabolism as a goal of obesity therapy. Physiol Behavior 85 (1): 25-35.

Belenky P, Bogan KL, Brenner C (January 2007). NAD + metabolism in health and disease. Trends Biochem. Science 32 (1): 12-9.

Jensen TE, Judge EA (2012). Regulation of glucose and glycogen metabolism during and after exercise. J. Physiol. (Lond.) 590 (part 5): 1069-76.

Resetar AM, Chalovich JM (1995). Adenosine 5 ′ - (gamma thiotriphosphate): an ATP analog that should be used with caution in muscle contraction studies. Biochemie 34 (49): 16039-45.

Image courtesy:

“Adenosine Diphosphate 3D Spheres” By Jynto (lecture) - Own work This chemical image was created with Discovery Studio Visualizer. (CC0) via Commons Wikimedia

“ATP-xtal-3D-balls” By Ben Mills - Own work (Public Domain) via Commons Wikimedia

“Adenosine diphosphate protonated” By NEUROtiker - Own work (Public Domain) via Commons Wikimedia

“Adenosine triphosphate protonier” By NEUROtiker - Own work, (Public Domain) via Commons Wikimedia