The Effect of Ageing on the Leghemoglobin of Cowpea Nodules

Experiments were conducted to study the effect of ageing of the host and senescence of the nodules on the content and composition of the proteins of leghemoglobin in nodules of cowpea (Vigna sinensis L.). Total and heme protein contents of leghemoglobin were the highest in the red nodules and dwindled with the onset of nodule senescence. In the fully senescent green nodules the total proteins decreased to a very low level, while the heme proteins were almost absent. Disc electrophoretograms of leghemoglobin obtained from red and brown nodules showed nine bands out of which only four gave positive test for heme. Greening of the nodules resulted in a considerable reduction in the intensity of the bands. Senescence of the host plant resulted in a reduction in the number of leghemo-globin proteins in all types of nodules and brought about a drastic change in their electrophoretic mobility.