On the synthesis of protoheme and peroxidase in suspension cultures of Nicotiana tabacum [tobacco]
1981
Maeder, M. | Fuessl, T. | Walker, E. (Heidelberg Univ. (Germany, F.R.). Inst. fuer Botanik)
The protoheme content of tobacco suspension cultures grown in continuous dark - yielding chlorophyll free cells - shows a peak on the 9th day of a two-week culture cycle. The peaks of enzymes of the porphyrin metabolism occur on the same day (porphobilinogenase) or one or two days earlier (delta-aminolaevulinic acid dehydratase). The ratio protoheme content/peroxidase activity - a value for non peroxidase-bound heme - increases markedly at the beginning of exponential growth then decreases to initial values after day 9. Representing the transition of exponential to stationary phase, day 9 is characterized by inhibition of protein, i.e., enzyme synthesis and by gradual decomposition of cellular structures. However, peroxidase synthesis continues beyond this transition. Various possibilities for protoheme supply are discussed.
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