Feedback regulation

In the biological systems the rates of several enzymes are altered through the presence of other molecules like as inhibitors and activators which are collectively known as effectors. A general theme in the control of metabolic pathways is when an enzyme early  on  in  the  pathway   is  reserved   through  an  end-product   of  the  metabolic pathway  in that  it is included.  This is called feedback inhibition and often takes place at the committed step in the path.  The  committed  step  is the first  step  to generate  an intermediate  that  is different to the pathway in question, and thus normally commits the metabolite  to  further  metabolism  along in which  pathway.  Control of the enzyme that carries out the committed step of a metabolic pathway conserves the metabolic energy provider of the organism, and prevents the build up of huge quantities of unwanted metabolic intermediates further along the pathway.

As various metabolic  pathways  are branched the feedback  inhibition  necessarily permit the  synthesis  of  one  product  of  a  branched  pathway  to  proceed  even  when another  is present  in excess. Here a procedure of sequential feedback inhibition may operate where the end-product of one branch of a pathway will inhibit the first enzyme after the branchpoint. When  this  branchpoint   intermediate   established  up,  it  in  turn  inhibits  the  first committed step of the overall pathway. Because the end-product  of  a  metabolic  pathway  including  multiple  enzyme  reactions  is unlikely  to resemble  the beginning  compound  structurally  the end-product  will bind to the enzyme at the control point at a site other than the active site. Like enzymes are forever allosteric enzymes.