Lipid Metabolism Vocabulary

Flashcards covering key vocabulary terms related to Lipid Metabolism, including digestion, absorption, oxidation, synthesis, and related enzymes and compounds.

Lingual Lipase

A lipase secreted by the dorsal surface of the tongue (Ebner’s gland) involved in lipid digestion in the mouth.

Gastric Lipase

An acid-stable lipase secreted by chief cells in the stomach, stimulated by Gastrin, with an optimum pH of about 5.4, responsible for up to 30% digestion of triglycerides in the stomach.

Steapsin

A powerful lipase (also known as pancreatic lipase) present in the pancreatic juice which is responsible for fat digestion in the small intestine.

Bile Salts

Effective emulsifying agents for fats, aiding in the digestion and absorption of lipids in the small intestine.

Chylomicrons

Assembly formed in the intestinal enterocyte, containing Apo B48, triacylglycerols, cholesterol esters, and phospholipids, for the export of lipids from intestinal cells to the lymphatics.

Beta-Oxidation

Process in which oxidation and splitting of two carbon units occur at the beta-carbon atom of fatty acids.

Carnitine Palmitoyltransferase 1 (CPT1)

Enzyme that modifies long-chain fatty-acyl-CoA to acylcarnitine for transport across the inner mitochondrial membrane.

Carnitine Translocase (CAT)

Transporter that moves acylcarnitine across the inner mitochondrial membrane.

Carnitine Palmitoyltransferase 2 (CPT2)

Enzyme that converts long-chain acylcarnitine back to long-chain acyl-CoA before beta-oxidation inside the mitochondria.

Acyl-CoA Dehydrogenase

Enzyme that catalyzes the initial dehydrogenation step in beta-oxidation, removing two hydrogens between carbons 2 and 3 of fatty acyl-CoA.

Enoyl-CoA Hydratase

Enzyme that catalyzes the hydration step in beta-oxidation, adding water across the double bond of enoyl-CoA.

3-Hydroxyacyl-CoA Dehydrogenase

Enzyme that catalyzes the second dehydrogenation step in beta-oxidation, generating NADH.

Beta-Ketothiolase

Enzyme that catalyzes the thiolytic cleavage step in beta-oxidation, cleaving the terminal acetyl-CoA group.

α-Oxidation

Alternative pathway for fatty acid oxidation involving decarboxylation of the COOH group after hydroxylation, forming a fatty acid with an odd number of carbon atoms, without initial activation of the fatty acid.

ω-Oxidation

Minor pathway occurring in microsomes, converting the CH3 group of a fatty acid to CH2OH and subsequently to a COOH group, producing dicarboxylic acids.

Fatty Acid Synthase System

Enzyme complex in the cytoplasm responsible for synthesizing fatty acids, mainly palmitic acid, from acetyl-CoA.

Acyl-CoA Synthetase

Enzyme that activates fatty acids by converting them to acyl-CoA, requiring ATP and CoA-SH.

Phosphatidic Acid

Intermediate in triacylglycerol and phospholipid synthesis, formed by combining two molecules of acyl-CoA with α-Glycero-P.

Choline Kinase

Enzyme that catalyzes the reaction of choline or ethanolamine with ATP to form corresponding monophosphates (phosphocholine or phosphoethanolamine).

Phosphocholine Cytidyl Transferase

Enzyme that further activates phosphocholine or phosphoethanolamine with CTP to form CDP-choline or CDP-ethanolamine.

Phosphocholine Diacyl Glycerol Transferase

Enzyme that catalyzes the reaction between CDP-choline (or CDP-ethanolamine) and 1,2-diacyl glycerol to form phosphatidyl choline (lecithin) or phosphatidyl ethanolamine (cephalin).

CTP-Phosphatidate Cytidyl Transferase

Enzyme that reacts CTP with phosphatidate to form CDP-diglyceride (cytidine diphosphate-diacyl glycerol).

CDP-Diacyl Glycerol Inositol Transferase

Enzyme that reacts CDP-diglyceride with inositol to form phosphatidyl inositol.

Linoleyl-CoA Desaturase

Enzyme that dehydrogenates linoleic acid after it is activated to form ‘LinoleylCoA’ to form “γ-linolenylCoA”.

ACAT (Acyl Cholesterol Acyl Transferase)

Enzyme that helps in the esterification of free cholesterol with saturated fatty acids for storage within the cell.

LCAT (Lecithin Cholesterol Acyl Transferase)

Enzyme that esterifies free cholesterol with poly-unsaturated fatty acids (PUFA).

Thiophorase

Enzyme that activates acetoacetate to acetoacetyl CoA in extrahepatic tissues, also called CoA transferase.

Apolipoprotein

The protein part of lipoprotein, synthesized mainly in the liver.

Ketogenesis

Process by which ketone bodies are synthesized exclusively by the liver mitochondria.

Ketolysis

The utilization of ketone bodies by extrahepatic tissues.