Chm 635-13 - -Oxidation & Fatty Acid Synthesis Compared...

Info iconThis preview shows pages 1–8. Sign up to view the full content.

View Full Document Right Arrow Icon
1 -Oxidation & Fatty Acid Synthesis Compared Oxidation Pathway Fatty Acid Synthesis pathway location mitochondrial matrix cytosol acyl carriers (thiols ) Coenzyme-A phosphopantetheine (ACP) e acceptors/donor FAD & NAD + NADPH -OH intermediate L D 2-C product/donor acetyl-CoA malonyl-CoA (& acetyl-CoA) A comparison of fatty acid oxidation and fatty acid biosynthesis. Page 931
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 Fatty Acids are Synthesized and Degraded by Different pathways Synthesis Degradation Cytosol Mitochondria ACP Coenzyme A Fatty acid synthase Absent Sequential addition of two-carbon units Malonyl ACP, driven by the release of CO 2 Reductant NADPH NAD + and FAD Formation of Malonyl-CoA Activates Acetate Units for Fatty Acid Synthesis The design strategy for fatty acid synthesis: 1) Fatty acid chains are constructed by the addition of two-carbon units derived from acetyl-CoA 2) The acetate units are activated by formation of malonyl-CoA (at the expense of ATP) 3) The addition of two-carbon units to the growing chain is driven by decarboxylation of malonyl-CoA 4) The elongation reactions are repeated until the growing chain reaches 16 carbons in length (palmitic acid) 5) Other enzymes then add double bonds and additional carbon units to the chain
Background image of page 2
3 Transfer of acetyl-CoA from mitochondrion to cytosol via the tricarboxylate transport system.
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
4 Cells Provide Cytosolic Acetyl-CoA and NADPH for Fatty Acid Synthesis The citrate-malate- pyruvate shuttle.
Background image of page 4
5 FOR SYNTHESIS Two important reactions to remember: 1. acetyl-CoA carboxylase reaction. 2. fatty acid synthase http://www.wiley.com/college/fob/quiz/quiz19/19-22.html
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
6 Fatty Acid Synthesis: Not exactly the reverse of Fatty Acid Breakdown Takes place in the cytoplasm Primarily in liver and adipose tissue. First step: CH 3 O S CoA CH 2 O S CoA O HO CO 2 , Biotin Acetyl CoA Carboxylase Acetyl CoA Malonyl CoA As with other carboxylation reactions, the enzyme prosthetic group is biotin . ATP-dependent carboxylation of the biotin, carried out at one active site 1 , is followed by transfer of the carboxyl group to acetyl-CoA at a second active site 2 . Acetyl-CoA Carboxylase catalyzes the 2- step reaction by which acetyl-CoA is carboxylated to form malonyl- CoA . ll Enzyme-biotin HCO 3 - + ATP ADP + P i Enzyme-biotin-CO 2 - O CH 3 -C-SCoA acetyl-CoA O - O 2 C-CH 2 -C-SCoA malonyl-CoA ll Enzyme-biotin 1 2
Background image of page 6
7 3. Synthesis of fatty acids 1. Acetyl CoA carboxylase Irreversible two-step reaction Bacteria – 3 polypeptide subunits Animal cells - one multifunctional polypeptide All cases, require a biotin prosthetic group CO 2 BIOTIN Biotin carrier protein - O C O Lys C=O H-N Biotin carboxylase C=O H-N Lys BIOTIN Transcarboxylase O = C - O 3. Synthesis of fatty acids 1. Acetyl CoA carboxylase C=O H-N Lys BIOTIN Transcarboxylase O = C - O
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 8
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 03/20/2012 for the course CHM 635 taught by Professor Dr.kavitashah during the Spring '11 term at Purdue University-West Lafayette.

Page1 / 23

Chm 635-13 - -Oxidation & Fatty Acid Synthesis Compared...

This preview shows document pages 1 - 8. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online