lecture 6 Flashcards
What are complex lipids used for?
- triacylglcerols which are a major store of energy
- part of cell membranes
- specialised signalling molecules called phosphatidyl inositol
how many fatty acids are turned over every 24 hours in a human body?
200g , accounts for 8% of the oxygen consumption
What is the major biosynthetic product?
palmitic acid
What is the experimental evidence that synthesis occurs in the cytosol?
- homogenise tissue and centrifuge
- get two components the pellet and the soluble faction
What can be found in the soluble fraction?
- protein precipitation with ammonium sulphate and split into multiple fractions.
What is the first step of fatty acid biosynthesis?
- carboxylation of Acetyl- CoA
- Acetyl- CoA is carboxylation to form malonyl-CoA
What is the name of the enzyme which catalyses the first step of fatty acid synthesis?
Acetyl CoA carboxylase, This is a two step process
What are the name of the two enzymes which make up Acetyl CoA carboxylase?
- Biotin carboxylase
- transcacrboxylase
What are the two reactants that are needed for the reaction for the carboxylation of acetyl - CoA?
ATP and Acetyl- CoA
What is the second step of fatty acid biosynthesis?
chain elongation
How does chain elongation occur?
1 acetyl CoA - primes the reaction, becomes the methyl terminus of the fatty acid chain
7 malonyl CoA provide 2 carbon unit to extend chain by 7*2 = 14 carbons
total chain length is 16
What is the overall reaction of fatty acid biosynthesis?
8 acetyl-CoA + 7ATP + 14NADPH + 14H+
goes to
palmitate + 8CoA + 6H2O + 7ADP + 7Pi + 14NADP
What are some facts about fatty acid synthase?
- is founding the cytosolic fraction of cells
- requires malonyl-CoA and acetyl - CoA
- requires NADPH
What are the common features of fatty acid synthase?
- relatively insoluble
- no , free unbound intermediates accumulate
- 4 phosphopantetheine required
