what is leghaemonglobin
Answers
Leghaemoglobin is a haemoprotein found in leguminous plants. The roots of such plants are in symbiotic relationship with a nitrogen fixing bacteria called as rhizhobium, present in the nodules. .Presence of oxygen in the roots of such plants ,reduces the activity of nitrogenase,an enzyme that is responsible for fixing atmospheric nitrogen. Leghaemoglobin,which is similar to haemoglobin in structural and chemical properties buffers the oxygen which is present in excess than needed for the survival of tissues of the root.The reddish pink color of the nodules, is in fact due to the presence of this leghaemoglobin.
simple langu......
Leghemoglobin is a nitrogen or oxygen carrier, because naturally occurring oxygen and nitrogen interact similarly with this protein; and a hemoprotein found in the nitrogen-fixing root nodules of leguminous plants. It is produced by legumes in response to the roots being colonized by nitrogen-fixing bacteria, termed rhizobia, as part of the symbiotic interaction between plant and bacterium: roots uninfected with Rhizobium do not synthesise leghemoglobin. Leghemoglobin has close chemical and structural similarities to hemoglobin, and, like hemoglobin, is red in colour. The holoprotein is widely believed to be a product of both plant and the bacterium in which the apoprotein is produced by the plant and the heme is produced by the bacterium. There is some evidence however suggesting that the heme moiety is also produced by the plant. In plants infected with Rhizobium, the presence of oxygen in the root nodules would reduce the activity of the oxygen-sensitive nitrogenase - an enzyme responsible for the fixation of atmospheric nitrogen. Leghemoglobin buffers the concentration of free oxygen in the cytoplasm of infected plant cells to ensure the proper function of root nodules. Leghemoglobin has a high affinity for oxygen, about ten times higher than the β chain of human hemoglobin. This allows an oxygen concentration that is low enough to allow nitrogenase to function but high enough so that it can provide the bacteria with oxygen for respiration
The nodules of root have adaptation to ensure that the enzyme nitrogenase is protected from oxygen( because that enzyme I'd highly sensitive to the molecular oxygen). To protect these enzyme , the nodules contain an oxygen scavenger called"leg-haemoglobin.