The specific activities of peroxidase and aminolevulinic acid dehydratase during the growth cycle of peanut suspension culture

Peroxidase (EC 1.11.1.7) enzyme units that were recovered by sequential extraction at low and high ionic strength buffer pH 7 from a peanut suspension culture at various intervals of cell growth appeared to increase with culture time. In particular, at the end of a 14-day growth cycle, peroxidase specific activity rose while protein content and the specific activity of porphobilinogen synthase (aminolevulinic acid, dehydratase EC 4.2.1.24) declined. The decrease of the protein content could probably be accounted for by the 95% decrease of protein synthesis at the end of the growth phase. The highest specific activity of aminolevulinic acid dehydratase (ALA dehydratase) appeared to be associated with organelles which could be precipitated at 500 × g and this specific activity appeared to be unaffected by the stage of growth of these cells. It is suggested that the ALA dehydratase activity in nonchlorophyllous peanut cells, which is as high as that found in green tissue, may play a function in the biosynthesis of the hemoprotein peroxidase.