Propionate in heme biosynthesis in soybean nodules

When soybean nodules are incubated with propionate-2-¹⁴C the heme moiety of leghemoglobin becomes labeled. The incorporation of propionate-2-¹⁴C into heme is linear with time and it appears that propionate is utilized without a lag period. The rate of incorporation of propionate-2-¹⁴C into heme is more rapid than the rate of incorporation of succinate-2-¹⁴C and citrate-1,5-¹⁴C, however, these rates of incorporation may be influenced by different sizes of endogenous pools of organic acids.