Answer to Question #297504 in Biochemistry for Water

Question

The enzymatic systems responsible for the de novo biosynthesis of saturated fatty acids

and polyketide natural products share many similarities including the utilization of

common precursors, similar chemistry, similar structures and overall architectural design.

Compare and contrast saturated fatty acid biosynthesis with polyketide biosynthesis to

explain how two systems are adapted for completely different functions. The former is

involved in primary metabolism and dedicated for synthesis of fatty acids whereas latter is

endowed with the task of creating a diverse range of complex natural products as shown

above.

Answer 1

Polyketide synthesis involves the assembly of basic carbon skeleton from acetate, propionate or butyrate while fatty acid synthesis is the creation of fatty acids from acetyl-CoA and NADPH through the action of enzymes called fatty acid synthases.

Fatty acid synthesis is essential in converting nutrients into metabolic intermediates for membrane biosynthesis, energy storage and the generation of signalling molecules, while polyketide synthesis is responsible for assembling activated carboxylic acids to elaborate chemical compounds using the C-C bond-forming condensation of an acyl moiety and carboxyacyl moiety.

The difference between Fatty acid synthesis and polyketide is that with polyketide synthase enzyme addition of the next building block may occur before reduction of the preceding unit is complete, leading to incorporation of double bonds of hydroxyls or keto into the growing chain which may lead to further transformations.