The key difference between choline and phosphatidylcholine is that choline is a quaternary ammonium compound while phosphatidylcholine is a derivative of choline made up of both choline and phosphoglyceric acid.
Choline and phosphatidylcholine are important components in the structure of a eukaryote. Both play an important role in membrane dynamics and membrane physiology of the cell. Due to its vital role in physiology, it is important to have a proper intake of these nutrients through dietary supplementation.
CONTENTS
1. Overview and Key Difference
2. What is Choline
3. What is Phosphatidylcholine
4. Similarities Between Choline and Phosphatidylcholine
5. Side by Side Comparison – Choline vs Phosphatidylcholine in Tabular Form
6. Summary
What is Choline?
Choline is an important nutrient for both plants and animals. It is a quaternary ammonium compound that is hygroscopic in nature. Choline is a colourless compound and relatively stable in aqueous solutions. The compound choline occurs as a cation. The available form of choline in the diet is as phospholipids or phosphatidylcholine. However, the de novo production of choline also takes place in both plants and animals.
Metabolism of choline happens in a similar fashion to amino acids. Choline absorption occurs in the intestines, where they undergo facilitated diffusion. Upon getting into the bloodstream, they are freely transported.
Figure 01: Choline
The biological role of choline is mainly structural. They form the phospholipid bilayer and help the membrane structure stability for various organelles. Further, it is also a component of the neurotransmitter acetylcholine and s–adenosyl methionine, which is important in the synthesis of homocysteine.
The richest source of choline is eggs, more precisely the egg yolk. In addition to this, meat, grain, vegetables and fruits also have high contents of choline. Choline deficiency is a rare condition in humans. However, it may lead to non-alcoholic fatty liver disease and damage to muscles.
What is Phosphatidylcholine?
Phosphatidylcholine is a type of phospholipid. The head group of it is the quaternary ammonium compound. Furthermore, the phosphatidylcholine is also called lecithin. The structure of phosphatidylcholine has a head group composed of choline and glycerophosphoric acid. It is a saturated fatty acid. They are yellow-brownish fatty substances.
Figure 02: Phosphatidylcholine
Phosphatidylcholine is mainly obtained through dietary sources such as eggs, meat, vegetables and wheat. However, de novo synthesis of phosphatidylcholine also takes place in eukaryotes.
The biological role of phosphatidylcholine varies rapidly. It acts as a structural component in the plasma membrane of eukaryotes. However, phosphatidylcholine is not present in bacteria. Furthermore, it is also a major component of pulmonary surfactant. Phosphatidylcholine also acts in the signalling mechanism and as cell signal mediators.
What are the Similarities Between Choline and Phosphatidylcholine?
- Choline and phosphatidylcholine act as structural components.
- They play an important role in membrane physiology.
- Both are absorbed into the blood at the small intestine.
- They travel freely in the blood.
- Both undergo facilitated diffusion during absorption.
- Moreover, they can be synthesized de novo in eukaryotic cells, including plants and animals.
- Furthermore, they can be obtained through the diet.
- Food items such as eggs, meat, vegetables and wheat have a high content of both compounds.
What is the Difference Between Choline and Phosphatidylcholine?
Both choline and phosphatidylcholine are important structural components in the system, mainly in eukaryotic cellular organization. The key difference between choline and phosphatidylcholine lies in their structure. Phosphatidylcholine is basically a derivative of choline. Therefore, phosphatidylcholine is more of a fatty acid while choline is a quaternary ammonium compound. Their main function is structural. However, the special functions differ in each compound. Another difference between choline and phosphatidylcholine is that choline is present in both eukaryotes and prokaryotes. Meanwhile, phosphatidylcholine is absent in prokaryotes.
The below infographic summarizes the difference between choline and phosphatidylcholine.
Summary – Choline vs Phosphatidylcholine
Choline and phosphatidylcholine are two compounds that are structurally important in membrane physiology. Therefore, there are essential compounds in the physiology of eukaryotes. Choline is a quaternary ammonium compound. In contrast, phosphatidylcholine is a combination of the choline head and phosphoglyceric acid. In addition to being structural components, they also have various metabolic functions. Dietary intake of these components is essential in order to maintain balance in the metabolic pathway. So, this summarizes the difference between choline and phosphatidylcholine.
Reference:
1. Meschino, James. “Choline and Phosphatidylcholine (Lecithin) .” Natural Health Products Compendium, Available here.
2. “Choline.” Wikipedia, Wikimedia Foundation, 16 Nov. 2019, Available here.
Image Courtesy:
1. “Choline-cation-3D-balls” By Jynto (talk) – Own workThis image was created with Discovery Studio Visualizer. (CC0) via Commons Wikimedia
2. “1-Oleoyl-2-almitoyl-phosphatidylcholine Structural Formulae V.1” By Jü – Own work (CC0) via Commons Wikimedia