Fatty Acid Oxidation

oleate C - 18, unsaturated palmitoyl carnitine Entry of carnitine into the mitochondrial matrix Mitochondria

Steps Involved in the Process

  1. Fats (triglycerides) must be mobilized
    1. hormone stimulation
    2. G - protein mediated conversion of ATP to CAMP by adenylate cyclase
    3. a kinase activates a lipase which converts triglyceride into glycerol and 3 fatty acids
  2. Fatty acids are complexed with proteins and transported through the blood
  3. they are then taken up by receptor mediated endocytosis

Beta Oxidation of Fatty acids

  1. Need carnitine carrier
  2. CoASH + acyl + carnitine --->translocase into mitochondria ---> CoASH
  3. Occurs in four steps
    1. oxidation
    2. hydration
    3. oxidation
    4. thiolysis
  4. For fatty acid chains with an odd number of carbons
    1. 1 Acetyl CoA + 1 Propionyl CoA --> Succinyl CoA --> Krebs

Metabolic Needs

  1. Brains must have glucose - no fat metabolism
  2. Animals cannot make glucose from fats
  3. If the body is low on glucose then the body shunts OAA to make glucose to feed the brain, the Kreb cycle slows down causing a loss of energy
  4. During severe starvation the body makes ketone bodies out of fatty acids (acetoacetic acid), this provides acetyl CoA for the brain, glucose comes from protein degradation
  5. Four carbon units are obtained from protein degradation

Fatty Acid Synthesis

  1. Occurs in cytosol
  2. intermediates attached to Acyl Carrier Protein (ACP)
  3. Reductant is NADPH
  4. Two carbon units are donated by malonyl CoA (not acyl CoA), driven by CO2 release
  5. Synthesis is by enzymes in a complex (FA synth), ACP is part of this
  6. Occurs in four steps
    1. Condensation
    2. Reduction
    3. Dehydration
    4. Reduction

Control of Fatty Acid Synthesis

  1. Malonyl CoA formation is the committed step (Acetyl CoA carboxylase)
    1. allosterically activated by citrate
    2. antagonized by palmitoyl CoA