TBL11 Flashcards
Metabolism of Fatty Acids and B Oxidation
Fatty Acids
- aliphatic
- esters in natural fats and oils
- free FAs in plasma
Nomenclature
Saturated acids
-anoic
Nomenclature
Unsaturated
-enoic
Eicosanoids: The 20-Carbon Powerhouses
- Derived from eicosanoic (20-carbon) polyenoic fatty acids
- Categories: Prostanoids, leukotrienes (LTs), and lipoxins (LXs)
- Role: Act as local hormones with significant physiological and pharmacological effects
Prostanoids
Includes prostaglandins (PGs), prostacyclins (PGIs), and thromboxanes (TXs)
Synthesis: Formed by cyclization of arachidonic acid to create a cyclopentane ring
Triacylglycerols (Triglycerides)
- Definition: Main storage forms of fatty acids
- Structure: Esters of glycerol (a trihydric alcohol) and three fatty acids
- Variants: Mono- and diacylglycerols found in tissues, significant in metabolism of triacylglycerols
- Carbon numbered in sn-# to indicate position
Phospholipids
Basic Structure: Derivatives of phosphatidic acid, consisting of a glycerol, a phosphate group, and two fatty acids
Types of Phospholipids: Examples include phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, and cardiolipin
Sphingolipids
Structure: sphingosine, phosphate, fatty acids
phospholipids
Phosphatidylcholines (Lecithins)
- most abundant in cell membranes
- crucial for choline storage and nervous transmission
- lung surfactant
Sphingomyelins
- location and function: outer leaflet of cell membrane lipid bilayer and myelin sheath around nerve fibers
- biological roles: cell signaling and apoptosis
phosphatidylinositol
in cell membrane
- function: cell signaling
- signaling pathway: involved in generating second messengers upon hormonal stimulation
Cardiolipin
in mitochondrial function
- location: exclusive to mitochondrial membranes
- role: essential for mitochondrial energy functions and implicated in diseases
- metabolic intermediates: lysophospholipid
Ergosterol
Vitamin D Synthesis
- in plants and yeast, dietary source of vit D
- Bioconversion: transforms into Vitamin D2 under UV light
Polyprenoids
- synthesized from isoprene units like cholesterol
- Ex: Ubiquinone, dolichols
impaired Fatty acid oxidation and associated diseases
Carnitine Deficiency
- Occurrence: Commonly seen in newborns, especially preterm infants, due to inadequate synthesis or renal leakage
- Symptoms: Hypoglycemia due to impaired fatty acid oxidation and muscle weakness from lipid accumulation
- Treatment: Oral supplementation of carnitine
impaired Fatty acid oxidation and associated diseases
Carnitine Palmitoyltransferase CPT Delivery
CPT-I Deficiency: Primarily affects the liver, leading to reduced fatty acid oxidation and ketogenesis, resulting in hypoglycemia
CPT-II Deficiency: Mainly impacts skeletal muscle
impaired Fatty acid oxidation and associated diseases
Jamaican Vomiting Sickness
- cause: eating unripe fruit of akee tree which contains hypoglycin
- hypoglycin inactivates acyl-CoA dehydrogenase, leading to hypoglycemia
impaired Fatty acid oxidation and associated diseases
Zellweger Syndrome
- severe condition, absence of peroxisomes in tissues
- accumulation of very long-chain FAs
- neurological symptoms: facial features similar to Down’s, hypotonia, feeding difficulties liver dysfunction, blindness, adrenocortical failure
- defective protein carrier: PMP70 peroxisomal membrane protein
Acetyl CoA shuttle as citrate
What has carriers in the IMM?
citrate, pyruvate, malate
Refsum disease
- defective enzyme: phytanoyl-CoA hydroxylase (PHYH) for alpha-oxidation
- Autosomal recessive
- accumulation of phytanic acid
- symptoms: weakness, blindness (retinitis pigmentosa), demyelinating neuropathy
- Treatment: restrict dietary intake of dairy and meat products
Transcription factors for lipogenic enzymes
Sterol regulatory element binding protein 1 c (SREBP-1c)
- Liver X receptor (LXR) stimulates SREBP1 gene
- Dietary polyunsaturated fatty acids (PUFA) inhibits SREBP1 gene
Transcription factors for lipogenic enzymes
Carbohydrate response element binding protein (ChREBP)
- Glucagon activated cAMP inhibits ChREBP
- Low energy activated AMP-activated protein kinase (AMPK) inhibits ChREBP
Regulation of Fatty Acid Synthesis
Glucagon
4 Regulation of Fatty Acid Synthesis
Insulin
