Fatty Acid Metabolism

Fatty AcylCoA synthetase

generates fattyacyl CoA which occurs in cytosol

-2ATPs

Beta Oxidation

FA’s are catabolized in the matrix by Beta Oxidation

Carnitine

carries long chain fatty acids which cannot be directly transported across the inner mitochondrial membrane into the matrix

Carnitine acyl transferase I

catalyzes the first committed step of beta-oxidation

Malonyl CoA

intermediate of FA biosynthesis and a negative allosteric affector of Carnitine Acyl Transferase I

Δ3-Enoyl CoA is generated when

an even numbered unsaturated FA has a double bond beginning on an odd-numbered C

is NOT a substrate for acyl-CoA DH or enoyl CoA but is a substrate for enoyl-CoA Isomerase

Enoyl-CoA Isomerase

converts Cis Δ3 Enoyl CoA into trans Δ2 acyl CoA which can then enter the beta-oxidation pathway

2,4 Dienoyl-CoA is generated when

an even numbered unsaturated FA has a double bond beginning on an even numbered C

2,4 -Dienoyl-CoA Reductase

converts 2,4-dienoyl-CoA to trans-Δ3-enoyl-CoA, facilitating beta-oxidation

-2.5 ATP from oxidation reaction

Dbs that start on even and odd carbons for even numbered unsaturated fatty acids have how many ATPs less than saturated fatty acids

db on even C = -2.5 ATP

db on odd C = -1.5 ATP

Propionoyl CoA are generated by

odd chain FA B oxidation

they are converted to Succinyl-CoA using Biotin and Cobalamin

Acyl CoA DH

oxidizes the C alpha and beta bond

Enoyl CoA Hydratase

adds H2O across the DB of a trans-enoyl CoA

B hydroxy CoA DH

oxidizes the B hydroxy group

-substrate is specific for L-hydroxyacyl-CoA

Thiolase

covalent catalysis

generates covalent thioester intermediate

reverse Claisen

Acetyl CoA Carboxylase

first committed step of fatty acid biosynthesis (acetate)

-uses bicarbonate and ATP and biotin

Unphosphorylated ACC

-binds to citrate with low kD/high affinity and becomes fully active in low citrate concentrations

-high ki for palmitoyl coA so high concentrations of palmitoyl coA is required to inhibit

Phosphorylated ACC

-reduced affinity for citrate so requires high concentrations of citrate to activate

-low ki for palmitoyl coA so low concentrations of palmitoryl coA are needed to inhibit