Difference Between ATPase and ATP Synthase

Key Difference – ATPase vs ATP Synthase
 

Adenosine triphosphate (ATP) is a complex organic molecule that participates in the biological reactions. It is known as “molecular unit of currency” of intracellular energy transfer. It is found in almost all forms of life. In the metabolism, ATP is either consumed or generated. When ATP is consumed, energy is released by converting into ADP (adenosine diphosphate) and AMP (adenosine monophosphate) respectively. The enzyme which catalyzes the following reaction is known as ATPase.

            ATP → ADP + Pi + Energy is released

In other metabolic reactions which incorporate external energy, ATP is generated from ADP and AMP. The enzyme which catalyzes the below-mentioned reaction is called an ATP Synthase.

            ADP + Pi → ATP + Energy is consumed

So, the key difference between ATPase and ATP Synthase is, ATPase is the enzyme that breaks down ATP molecules while the ATP Synthase involves in ATP production.

CONTENTS

1. Overview and Key Difference
2. What is ATPase
3. What is ATP Synthase
4. Similarities Between ATPase and ATP Synthase
5. Side by Side Comparison – ATPase vs ATP Synthase in Tabular Form
6. Summary

What is ATPase?

The ATPase or adenylpyrophosphatase (ATP hydrolase) is the enzyme which decomposes ATP molecules into ADP and Pi (free phosphate ion). This decomposition reaction releases energy which is used by other chemical reactions in the cell. ATPases are the class of membrane-bound enzymes. They consist of a different class of members that possess unique functions such as Na⁺/K⁺-ATPase, Proton-ATPase, V-ATPase, Hydrogen Potassium–ATPase, F-ATPase, and Calcium-ATPase. These enzymes are integral transmembrane proteins. The transmembrane ATPases move solutes across the biological membrane against their concentration gradient typically by consuming the ATP molecules. So, the main functions of the ATPase enzyme family members are moving cell metabolites across the biological membrane and exporting toxins, waste and the solutes that can hinder the normal cell function.

A very important example is Sodium/Potassium exchanger ATPase (Na⁺/K⁺-ATPase) that involves in maintaining cell membrane potential. The Hydrogen/Potassium ATPase (H⁺/P⁺-ATPase) acidifies the stomach which is also known as “gastric proton pump.” Some of the ATPase enzymes are working as cotransporters and pumps. Active transportation is the movement of molecules across a membrane from lower concentration region to a higher concentration region of molecules against a concentration gradient. Secondary active transportation involves the electrochemical gradient. The cotransporters are used in the secondary active transportation of molecules. The Na⁺/K⁺-ATPase is a well-known cotransporter which causes the net flow of charge.

ATPase Classification

There are different ATPases. They differ in function, structure and the ions they transport. ATPases are classified as bellow,

• F-ATPase – It is found in bacterial plasma membranes, mitochondria, and chloroplast. The water-soluble part of F₁ section hydrolyzes ATP.
• V-ATPase – It is found in the eukaryotic vacuoles. It catalyzes ATP hydrolyzing in organelles like proton pump of lysosome to transport solutes.
• A-ATPase – Archaea has A-ATPase. They function like F-ATPase.
• P-ATPase – It is found in bacteria, fungi and eukaryotic membranes and organelles. It functions as ion transporters across the membrane.
• E-ATPase – A cell surface enzyme involves hydrolyzing NTPS including extracellular ATP.

What is ATP Synthase?

This is the enzyme that creates ATP (energy storage molecules). The overall reaction that catalyzing ATP synthesis is as bellow,

ADP + Pi + H⁺ (out) ⇌ ATP + H₂0 + H⁺ (in)

As this reaction is energetically unfavorable (ATP from ADP) it takes place in the reverse direction. It does have major two regions in the enzyme structure. This has a rotational motor structure allowing ATP production. They are F1 (fraction 1) region and F₀ (fraction zero) region. Because of this rotational mechanism (molecular machine) the F₀ region drives the rotation of F₁region. F₀ region has C-ring and other subunits like a, b, d and F₆. F₁ region has alpha, beta, gamma and delta subunits. F₁ and F₀ collectively create a pathway for proton movement across the membrane. They mainly produce more ATP molecules in electron transport chain through oxidative phosphorylation.

What are the Similarities Between ATPase and ATP Synthase?

• Both regulate the number of ATP molecules in the cell.
• Both are multi subunits enzymes.
• Both can regulate the movement of molecules across the membrane.
• Both are heavy molecular weight enzymes.
• Both are enzymes that are protein in nature.

What is the Difference Between ATPase and ATP Synthase?

Summary – ATPase vs ATP Synthase 

ATP production and hydrolyzing processes are found in almost all forms of life. In the metabolism reactions either they are consumed or regenerated. When they are consumed, energy is released. ADP (adenosine diphosphate) and AMP (adenosine monophosphate) are produced during the ATP breakdown. The enzyme catalyzing the ATP breakdown reaction is known as ATPase. In other metabolic reactions, ATP is generated from ADP and AMP. The enzyme catalyzing the ATP production reactions is called an ATP Synthase. This is the difference between ATPase and ATP Synthase.

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Reference:

1.“ATPase.” Wikipedia, Wikimedia Foundation, 6 Nov. 2017, Available here  
2.“ATP synthase.” Wikipedia, Wikimedia Foundation, 9 Nov. 2017, Available here  

Image Courtesy:

1.’Blausen 0818 Sodium-PotassiumPump’By Blausen.com staff (2014). “Medical gallery of Blausen Medical 2014”.  WikiJournal of Medicine 1 (2). DOI:10.15347/wjm/2014.010. ISSN 2002-4436. – Own work (CC BY 3.0) via Commons Wikimedia 
2.’Figure 07 04 02′ By CNX OpenStax  (CC BY 4.0)  via Commons Wikimedia