Fatty Acid Synthesis

[[Cell Metabolism]]

Lipid Synthesis/Fatty Acid Synthesis

FAS Regulation

Functions/Purpose:

• Palmitate - a precursor for the variety of other fatty acids

• Phospholipids

• Membranes • Signal Transduction – Cell-cell, Contact growth, Phagocytosis, Aid nerve impulses • Hormones - prostaglandins

====Fundamentals:====
''Phases:''
1-Preparation – acetyl CoA transferred from mitochondria to the cytoplasm
    Transported via citrate and cleaved to give AcCoA and OAA
2-Activation - Acetyl CoA is activated to malonyl CoA
3-Elongation - intermediates attached to an acyl carrier protein
two carbons at a time
five step elongation cycle
LINKS
    Citrate - TCA
Citrate is a sign that energy needs have been met
    14 NADPH – PPP
    ATP – Glycolysis and ETC
Synthesis fo Palmitate
    8 AcCoA
    14 NADPH
Phase 1    PREPARATION (8 NADPH used) – CYTOSOL/MITO
Citrate is shuttled out of mito – 2 fates:
    AcCoA
    OAA
        OAA – cyto malate dehydrogenase - malate
        Malate – malic enzyme - Pyruvate + NADPH
Pyruvate enters mitochondria either from Glycolysis or above pathway
''Phase 2    ACTIVATION - CYTOSOL''
STEPS   
1    AcCoA + Bicarbonate + ATP – (AcCoA Carboxylase) – Malonyl CoA
        Biotin Required – prosthetic group
''Phase 3    ELONGATION – CYTOSOL''
    AcCoA (cytosol) + ACP -> AcCoA ACP
    Malonyl CoA + ACP -> Malonyl ACP
STEPS
1    Condensation:
AcCoA ACP + Malonyl ACP –acy-malonyl ACP reducing enzyme - Acetoacetyl ACP
Condensation
        Releases CO2
2    Reduction:
Acetoacetyl ACP + NADPH – beta-ketoacyl ACP reductase – D-3-ydroxybutyryl ACP
3    Dehydration:
D-3-ydroxybutyryl ACP – 3-hydroxyacyl ACP dehydratase – crotonyl ACP
4    Reduction:
Crotonyl ACP + NADPH – enoyl ACP reductase – butyryl ACP
5    Repeat 1 (product ACP + Malonyl ACP)
N    Termination
C16-ACP – thioesterase – C16+ACP
    Specific for C16
====Additional Information:====