Why does feedback inhibition occur at the first committed step in a pathway?
Many pathways have a common beginning and then branch off to form specific products, this is advantageous because then less anzymes are required to get the job done. In order to inhibit one pathway specifically, you need to inhibit the “first committed step” – this means that this is the first step in the pathway that goes only to those specific products – including the one that is capable of feedback inhibiting the pathway. Many of these pathways are necessary – turning down most of them is not going to support life. The key is that metabolism involves an interwoven series of pathways and those that are not necessary at the moment can be shut down to conserve energy – but the rest must remain functional.
