Question

Outline the role and mechanisms that anaplerotic reactions play in microbial anabolism. Use diagrams to illustrate your answer.

Answer 1

As intermediates of the citric acid cycle are removed to serve as biosynthetic precursors,they are replenished by anaplerotic reactions.

The reaction concerned to replenish or to fill up the intermediates of citric acid cycle are called anaplerotic reaction or anaplerosis(Greek:Fill up).

Under normal circumstances the reaction by which cycle intermediates are siphoned off into other pathways and those by which they are replenished are in dynamic balance,so that the concentration of the Citric Acid Cycle intermediates remain almost constant.

Biosynthetic products(in blue) are derived from precursor metabolites ,which are intermediates of amphibolic pathways. Two major anaplerotic reactions are shown in green.These reactions ensure an adequate supply of Citric Acid Cycle derived precursor metabolites and are especially important to fermentative organisms in which only certain Citric Acid Cycle reactions operate.