Lipid Metabolism Flashcards
Where does FA synthesis occur?
Cytosol
What compounds are required for FA synthesis?
Acetyl CoA
NADPH
What produces Acetyl CoA in the mt matrix?
Pyruvate Dehydrogenase complex
How is Acetyl CoA transported into the cytosol?
- Acetyl CoA + Oxaloacetate —> Citrate (citrate synthase)
- Citrate is carried across membrane to
Cytosol and converted back to Acetyl CoA and OAA
How is OAA returned to the mitochondria inFA Synthesis?
- Converted to Malate via Malate dehydrogenase
- Malate converted to pyruvate and CO2 via MAlic enzyme and NADP+
- Pyruvate has a Carrier which allows transport across membrane
- Pyruvate Carboxylase catalysis:
Pyr + ATP + Biotin + CO2 —> OAA
What happens to Acetyl CoA once in the cytosol in FA synthesis?
Converted to Malonyl CoA via Acetyl CoA carboxylase
What is the coenzyme used in production of malonyl CoA?
Biotin
Why is consumption of Raw egg not recommended?
Raw egg contains Avidin, which can tie up biotin in other physiological processes.
What are the components of FA synthase?
Acetyl Transferase (AT) Malonyl Transferase(MT) Keto Synthase (CE) B-ketoacyl reductase (KR) Dehydratase (DH) Enology Reductase (ER) Thioesterase (TE)
What is Phosphopantetheine? How is is attached to ACP Protein?
Prosthetic group which anchors the growing fattyacyl chain during FA synthesis
Attached covelantly
What is the role of Thioesterase I in Fatty Acid synthase?
Cleaves off the final product palmitate
What is Thioesterase II?
An independents protein in mammary glands which binds FA synthase causing premature release of short fatty acid chains
What are the first two rounds of FA synthesis?
- Butyryl-ACP formation
2. C-6 Formation
What is the #C and Bond numbers of palmitoleic acid?
16:2 (9,10)
What is the #C and Bond numbers of Oleic acid?
18:2 (9,10)
What is the important of thioesterase II activity for infants?
Smaller FA chains such as Capric, Lauric, and myristic acid are easy to digest compared to palmitic
What are the primary products of FA oxidation?
NADH, FADH2, and Acetyl CoA
Where does FA degradation occur?
Cytosol
How is Fatty Acyl CoA transported into the mitochondria?
It is converted into fatty acyl Carnitine via Carnitine Acyltransferase
Describe Carntineacyl-carnitine translocase disease?
- Autosomal recessive mutation
- Causes hypoketosis
- Affects Liver, Cardiac muscle, skeletal muscle, arrhythmia
What is the Net yield ATP from one Palmitate?
129 ATP
How does oxidation of odd-number FAs differ?
Last product is Propionyl CoA
How is propionyl CoA broken down?
- Prop CoA carboxylase converts to D-methyl malonyl CoA
- Converted to L-methyl malonyl CoA
- Converted to Succinyl CoA via Methyl Malonyl CoA mutate and enters TCA
What two compounds are necessary for breakdown of odd number FAs?
Biotin - Prosthetic group for PC carboxylase
Vitamin B12 - Coenzyme for MMC Mutase
What is an example of alpha oxidation?
Digestion of Phytanic acid in dairy products and chlorophyll
What enzyme hydroxylates phytanic acid?
A-hydroxylase
What is important about omega-oxidation?
- Significant for short chain fatty acids
- Involves oxidation of omega-methyl or adjacent methylene carbons
What are the two allosteric regulators of FA synthesis/breakdown?
- Citrate - activates ACC
2. Malonyl CoA - Inhibits carnitine acyltransferase
What s Refsum Disease?
- Deficiency in alpha-hydroxylase enzyme
- Accumulation of phytanic aid in plasma and nerve tissue
- Leads to neurological damage
Describe SIDS (Sudden Infant Death Syndrome)
- Medium chain FA CoA dehydrogenase deficiency
- Freq: 1: 10,000
- Autosomal recessive
Describe methylmalonic acidemia
- Methylmalonyl CoA mutate sometimes missing
- Sometimes B12 missing
- Causes metabolic acidosis and retardation
Describe the development of diabetic ketoacidosis
A. Increased glucagon/insulin ratio cause elevated cAMP in lover, resulting in decreased malonyl CoA
B. CPT-1 De-inhibition resulting in a activation Of FA oxidation
C. Mor Acetyl CoA produced leading to increased Ketone Bodies
