What is the main enzyme in cholesterol synthesis?
Abstract. In eukaryotes, 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase is a key enzyme that catalyses the synthesis of a precusor of cholesterol as well as non-sterol isoprenoids, mevalonate.
How HMG-CoA is formed write its fate?
β-Hydroxy β-methylglutaryl-CoA (HMG-CoA), also known as 3-hydroxy-3-methylglutaryl coenzyme A, is an intermediate in the mevalonate and ketogenesis pathways. It is formed from acetyl CoA and acetoacetyl CoA by HMG-CoA synthase.
What type of inhibitor is HMG-CoA reductase?
A substance that blocks an enzyme needed by the body to make cholesterol and lowers the amount of cholesterol in the blood. HMG-CoA reductase inhibitor drugs are called statins. Also called hydroxymethylglutaryl-coenzyme A reductase inhibitor.
Where is HMG-CoA reductase produced?
In humans, the gene for HMG-CoA reductase (NADPH) is located on the long arm of the fifth chromosome (5q13. 3-14). Related enzymes having the same function are also present in other animals, plants and bacteria.
What is the function of the enzyme HMG-CoA reductase?
Function. HMG-CoA Reductase (or 3-hydroxy-3-methyl-glutaryl-CoA reductase or HMGR) is the rate-controlling enzyme of the mevalonate pathway, responsible for cholesterol and other isoprenoid biosynthesis. HMGR is a transmembrane protein, containing 8 domains, that is anchored in the membrane of the endoplasmic reticulum …
What is the chemical structure of cholesterol?
Cholesterol is a 27 carbon compound with a unique structure with a hydrocarbon tail, a central sterol nucleus made of four hydrocarbon rings, and a hydroxyl group. The center sterol nucleus or ring is a feature of all steroid hormones.
What is the ring structure present in cholesterol?
Cholesterol (3-hydroxy-5,6-cholestene) is a steroid and contains the carbon skeleton of cyclopentanoperhydro-phenanthrene, which consists of three six-membered rings and a five-membered ring.
What is the structure and function of cholesterol?
Cholesterol is a structural component of cell membranes and serves as a building block for synthesizing various steroid hormones, vitamin D, and bile acids. Besides their structural role providing stability and fluidity, cholesterol also plays a crucial role in regulating cell function.
What class of enzyme is dehydrogenase?
A dehydrogenase is an enzyme belonging to the group of oxidoreductases that oxidizes a substrate by reducing an electron acceptor, usually NAD+/NADP+ or a flavin coenzyme such as FAD or FMN.
Where is HMG-CoA reductase located?
the endoplasmic reticulum
HMG-CoA reductase is anchored in the membrane of the endoplasmic reticulum, and was long regarded as having seven transmembrane domains, with the active site located in a long carboxyl terminal domain in the cytosol.
What is the major regulatory enzyme for cholesterol synthesis?
The major regulatory enzyme is HMG-CoA reductase. Cholesterol synthesis takes place in the liver and intestinal mucosa. Acetoacetyl CoA. Cholesterol: Oxidized to bile acids in liver; precursor for steroid hormones.
What is the role of HMG CoA reductase in cholesterol biosynthesis?
HMG-CoA reductase is the first and rate-limiting enzyme in the cholesterol biosynthetic pathway and is the target of statins, which effectively lowers serum cholesterol by decreasing hepatic production of cholesterol [2,3].
What is the function of the enzyme cholesterol oxidase?
Cholesterol oxidase is a bacterial-specific flavoenzyme that catalyzes the oxidation and isomerisation of steroids containing a 3beta hydroxyl group and a double bond at the Delta5-6 of the steroid ring system. The enzyme is a member of a large family of flavin-specific oxidoreductases and is found …
How many classes of coenzyme A reductase are there?
Bochar D.A., Stauffacher C.V., Rodwell V.W. Sequence comparisons reveal two classes of 3-hydroxy-3-methylglutaryl coenzyme A reductase. Mol. Genet. Metab. 1999; 66 :122–127. doi: 10.1006/mgme.1998.2786.