Bemerkungen zu der Arbeit von O. H. Frankel

Synthesis of Protoheme via Both, the C5-and the Shemin-Pathway, in the Pigment Mutant C-2 A′ of Scenedesmus obliquus

“…This m utant was chosen for the experiments since the existence of the two p ath ways to 5-aminolevulinic acid had been proven be fore [5,6] and, furtherm ore, since the form ation of ALA and the subsequent steps o f tetrapyrrole bio synthesis are performed at high rates during green ing of the m utant in the light. The cultures were harvested aseptically when they had reached a density o f 10-11 jj.1 PCV m l-1, were resuspended in inorganic medium and then transferred into light for greening.…”

“…In Cyanidium caldarium [13] and maize [14] all hemes are formed exclusively via the C5-pathway. In the unicellular green alga Scenedesmus obliquus the existence of both pathways up to ALA was de m onstrated by specific labeling and ALA accumu lation after the inhibition of ALA-dehydratase [5][6][7][8], In a preceeding paper a method was pre sented describing as well the labeling of hemes in Scenedesmus with [14C]precursors of both path ways to ALA as how to extract and purify them [15], In the present paper further evidence for the participation o f both pathways in heme biosyn thesis is given, focussing on the distribution of the pathways in plastidic and mitochondrial heme bio synthesis in the light-dependent greening mutant C-2 A' of the unicellular green alga Scenedesmus obliquus.…”