Difference Between Cholesterol and Cholesteryl Ester

Key Difference – Cholesterolvs Cholesteryl Ester

Cholesterol is an importantsterolcomponent in animals. It has both structural and functional roles to play in a cellular system. And also cholesterol is an important constituent inHigh Density Lipoprotein (HDL) and Low Density Lipoprotein (LDL). Therefore, it plays a major role in cardiovascular health. Cholesterol and cholesteryl esters are two forms in which cholesterol exists in an animal. Cholesterol is a sterol with a four-membered ring structure with a singlehydroxylgroup attached to one of the rings. It is the active, raw form of cholesterol. Cholesteryl Ester is the inactive form in which cholesterol is esterified withfatty acidsin order to be transported to target organs. Thekey differencebetween cholesterol and cholesteryl esters is the active and the inactive forms.Cholesterol is an activesterolform whereas cholesteryl ester is an inactive esterified form in which cholesterol is transported in thecirculatory系统。

CONTENTS

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

What is Cholesterol?

Cholesterol is a type of sterol which can be synthesized in the animal hepatic cells with the assistance of the key regulatory enzyme HMG CoA reductase or 3-hydroxy-3-methyl-glutaryl-CoA reductase. Cholesterol can also be obtained via the diet through animal-based food. Thus there are two main sources in which the animal body satisfies its need for cholesterol. The molecular formula of cholesterol is C₂₇H₄₅OH. The structure of cholesterol has three main regions; the hydrocarbon chain, the ring structure with four rings and the characteristic hydroxyl group. Due to the presence of thehydrophilichydroxyl group and the hydrophobic hydrocarbon region cholesterol is termed as an amphipatic molecule. It is slightly soluble in water and forms micelle structures.

Cholesterol acts as a structural component inplasma membranes. Cholesterol also increases the fluidity of the membrane. Moreover, cholesterol is a precursor of allsteroidhormones which includetestosteroneand estrogen. The function of Cholesterol is categorized into two main types; High density lipoprotein cholesterol or HDL Cholesterol and Low Density Lipoprotein Cholesterol or LDL Cholesterol. These lipoproteins act as carriers for cholesterol. LDLs carry cholesterol out of the liver and deposit in the periphery. HDL carries cholesterol into the liver. Both these types are vital for cardiovascular health. It is identified that LDL cholesterol is the bad form of cholesterol which leads to the risk ofcardiovascular diseases. In contrast, HDL Cholesterol is termed as the good cholesterol as it reduces the risk of cardiovascular diseases.

What is Cholesteryl Ester?

Cholesteryl ester is the inactive form of cholesterol. Cholesteryl Esters are formed when cholesterol is esterified with fatty acids. This is completely hydrophobic. The main importance of converting cholesterol to cholesteryl esters is to facilitate efficient transportation of cholesterol. This conversion increases the amount of cholesterol that can be packaged into the interior of thelipoproteinthus, facilitating more efficient transportation of cholesterol in the blood. The raw cholesterol only binds to the outer surface of the lipoprotein. Therefore, less amount of cholesterol can be carried in the blood.

The conversion of cholesterol to cholesteryl esters is an enzyme-mediated process. There are two main enzymes involved in this process. The type of enzyme depends on location in which the esterification reaction takes place. In the peripheral tissue, the esterification process is carried out by lecithin-cholesterol acyltransferase (LCAT). The fatty acid moiety used in the esterification reaction is donated by the substrate phosphatidyl choline. In the intestinal lumen, the enzyme acyl-coenzyme A (CoA): cholesterol acyltransferases (ACATs) is used. There are two main types of ACATs. ACAT 1 is found in every tissue whereas ACAT 2 is found specifically in the liver and the intestinal lumen. ACAT uses acyl CoA for the esterification process.

什么是re the Similarities Between Cholesterol and Cholesteryl Ester?

• Both contain a four-ringed hydrocarbon structure.
• Both can be packaged into lipoproteins.
• Both play a functional role in cardiovascular health and cardiovascular diseases.

What is the Difference Between Cholesterol and Cholesteryl Ester?

Cholesterol vs Cholesteryl Ester
Cholesterol is a compound of the sterol type found in most body tissues.	Cholesteryl Ester is a derivative of cholesterol in which an ester bond is formed between the carboxylate group of a fatty acid and the hydroxyl group of cholesterol.
Structure
Cholesterol contains a sterol structure with a hydroxyl group.	Cholesteryl Ester contains esterified structure with nonpolar groups.
Polarity
Cholesterol is an amphipathic molecule.	Cholesteryl Ester is a hydrophobic and a nonpolar molecule.
Solubility in water
Cholesterol is sparsely soluble in water.	Cholesteryl Ester is insoluble in water.
Form
Cholesterol is the active raw form.	Cholesteryl Ester is an inactive form .

Summary – Cholesterolvs Cholesteryl Ester

Cholesterol and cholesteryl esters are the two main forms of cholesterol in the body. Cholesterol is the raw form which is composed of a sterol structure. In order to facilitate efficient packaging and transportation of cholesterol, it is converted to cholesteryl esters by two main enzymes, LCAT and ACAT. Hence cholesteryl ester is derived from cholesterol. This is the difference between cholesterol and cholesteryl ester.

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Reference:

1.“Cholesterol Esterification.” Sigma-Aldrich.Available here

image Courtesy:

1.’Cholesterol (chemical structure)’By Wesalius – Own work, Public Domain viaCommons Wikimedia
2.’Cholesteryl palmitate’By Ayacop – Own work, Public Domain viaCommons Wikimedia