Study Set Content:
Rickets(children); skeletal deformities, impaired growth
Vitamin D
Subdermal hemorrhaging
Vitamin K
Osteomalacia, soft bending bones
Vitamin D
BIOSYNTHESIS OF FATTY ACIDS• The pathway occurs in the
cytosol
BIOSYNTHESIS OF FATTY ACIDSBIOSYNTHESIS OF FATTY ACIDS This system is present in many tissues, including
– Liver – Kidney – Brain – Lungs – Mammary glands – Adipose tissues
BIOSYNTHESIS OF FATTY ACIDS Cofactor requirements are
NADPH – ATP – Mn2+ – Biotin – HCO3 - (source of CO2 )
is the immediate substrate and free palmitate is the end product
Acetyl CoA
STEP 1
PRODUCTION OF MALONYL COA IS THE INITIAL AND CONTROLLING STEP IN FATTY ACID SYNTHESIS
as a source of carbon dioxide is required in the initial reaction for the carboxylation of Acetyl CoA to Malonyl CoA in the presence of ATP and the enzyme, Acetyl CoA carboxylase
Bicarbonate ion
The enzyme Acetyl CoA carboxylase has a requirement for the B vitamin,
Biotin
•The reaction takes place in two steps:
1) carboxylation of biotin involving ATP, and (2) transfer of the carboxyl group to acetyl CoA to form malonyl CoA
STEP 2:
FATTY ACID SYNTHASE COMPLEX
In the primary structure of the protein, the enzyme domains are linked in the sequence
N-Ketoacyl synthase-Maolnyl/acetyl transacylase-Hydratase-Enoyl reductase-Ketoacyl reductase-ACP-Thioesterase-C
The Main Source of NADPH for Lipogenesis Is the
Pentose Phosphate Pathway
is involved as donor of reducing equivalents in both the reduction of the 3-ketoacyl and of the 2,3-unsaturated acyl derivatives (reactions 3 and 5)
NADPH
are the chief source of the hydrogen required for the reductive synthesis of fatty acids.
The oxidative reactions of the pentose phosphate pathway
Significantly, tissues specializing in active lipogenesis—also possess an active pentose phosphate pathway.
liver, adipose tissue, and the lactating mammary gland—
• Moreover, both metabolic pathways are found in the
Cytosol of the cell
Elongation of Fatty Acid Chains Occurs in the
Endoplasmic Reticulum
elongates saturated and unsaturated fatty acyl-CoAs (from C10 upward) by two carbons, using malonyl-CoA as the acetyl donor and NADPH as the reductan
(microsomal system)
