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18 Cards in this Set
- Front
- Back
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2 biggest processes in FA metabolism
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fatty acid synthesis and
beta oxidation |
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Principles of biosynthesis
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in cytoplasm
uses acyl carrier protein (ACP) major enzyme is fatty acid synthase Adds activated 2 C units from malonly ACP Nadph is e- source complete at palmitate C16 |
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3 phases
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1=get acetyl coA out of mito.
2=activate them by adding CO2 addition of acetyo and malonyl to ACP 3=condensation and reduction |
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Phase 1=transfer of Acetyl CoA to cytoplasm
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1=OAA and Acetyl CoA combine to citrate
2=citrate goes through citrate transporter in inner membrane and out into cytosol 3=enzyme citrate lyase turns back to OAA and Acetyl CoA 4=NADPH formed in process *this and pentose phosphate shunt are two main sources of NADPH* |
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Phase 2=
activation of Acetyl CoA to malyonyl coA and transfer to ACP |
1=Acetyl CoA carboxylase makes AcoA into malonyl CoA, uses ATP, HCO3-,and BIOTIN which adds C02
2=malonyl CoA ACP transcyclase take 3 malyonyl and adds to ACP(acyl carrier protein) to make malonyl ACP 3=Acetyl CoA added to ACP by Acetyl coA-ACP transcyclase to make Acetyl Acyl Carrier Protein (acetyl ACP) |
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Regulation of Acetyl Co A carboxylase
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Hormonal
1=Insulin stimulates 2=glucagon inhibits 3=epinephrine inhibits Allosteric Citrate stimulates Palmitoyl CoA inhibits AMP inhibits Local Control= binding of citrate to a pi thus inactive carboxylase will partially activate it |
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Phase 3=
Condensation and Reduction |
Fatty Acid Synthase-7 enzymatic activities
Dimer w/3 domains Major enzyme here All the following steps are in this phase |
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Fatty Acid Synthase
First Domain/subunit |
Substrate Entry and
Condensation unit 1=acetyl transferase accepts ACoA, transfers to Condensing Enzyme 2=malonyl transferase accepts malonly CoA, tansfers to ACP 3=Beta ketoacyl synthase=condensing enzyme *ACP and CE come together and form a 4 carbon chain (C02 released) which is held in ACP site* |
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Fatty Acid
Second Domain/subunit |
beta ketoacyl reductase reduces (takes H from NADPH leaves NAD)
beta hydroxy acyl dehydratse dehydrates enoyl reductase reduces (takes H from NADPH leaves NAD) |
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Fatty Acid Synthase
Third Domain/subunit |
thioesterase
recognizes when chain has grown to 16C and will chop it off |
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Role of mixed function oxidases
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takes 2 substrates one fatty acid with double bond one without, adds them together and makes a bigger unsaturated fatty acid.
done by fatty acid acyl CoA desaturase |
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Elongation
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in smooth er and mito.
addition of 2C units from Acetyl CoA to the fatty acid chain adrenoleukodystrophy=cant oxidize long chains of sat. so feed long chains of unsat to compete |
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Omega nomenclature
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start at opposite end of C00- functional group and count to first double bond and call omega
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Essential fatty acids
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we can't desat. past a double bond at position 9 so we need to uptake essential fatty acids with desaturation past C 9 to make important things like Arachidonic acid=signal mol.
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Regulation of fatty acid oxidation
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Malonly C0A=inhibits carnitine palmitoyl transferase CAT-1 which takes malonyl into matrixx
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Synthesis of Ketone Bodies
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Happens when you have too much Acetyl CoA
1=combine 2 ACoA (thiolase) 2=add 2 more ACoA, now a 6C (HMG CoA synthase) 3=Clip off 2C to be 4 C (HMG CoA lyase) 4=leaves with 4 C Acetoacetate (a ketone body) 5=can degrade into acetone and beta hydrowybuterate (other 2 ketone bodies) |
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Catabolism of ketone Bodies
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1=start with beta hydroxybuterate
2=transfer a CoA from succinyl Co A to it (beta keto co A transferase) 3=cleave it and you get to Acetyl CoA *organisms that have succinyl co a can use this mechanism to degrade ketone bodies for use, turn into Acety Co A for TCA cycle* |
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Regulation of Fatty Acid Oxidation
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insert picture from lecute 62 add page 1
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