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BIOSYNTHETIC PATHWAYS TO 6‐AMINOLEVULINIC ACID INDUCED BY BLUE LIGHT IN THE PIGMENT MUTANT C‐2A‘ OF SCENEDESMUS OBLIQUUS *
Author(s) -
Klein Otto,
Senger Horst
Publication year - 1978
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1978.tb07589.x
Subject(s) - dehydratase , scenedesmus obliquus , pigment , mutant , levulinic acid , glycine , biochemistry , chlorophyll , chemistry , alanine , amino acid , biology , enzyme , botany , algae , organic chemistry , gene , catalysis
The X‐ray induced mutant C‐2A of Scenedesmus obliquus grows heterotrophically but forms only traces of chlorophyll in the dark. Upon illumination, baminolevulinic acid (ALA) is synthesized and chlorophyll is formed. These processes are blue light dependent and cease immediately when the cells are transferred back into darkness. Addition of levulinic acid (LA) inhibits the light‐dependent formation of chlorophyll and causes accumulation of ALA by competitive inhibition of the ALA dehydratase (EC. 4.2.1.24). By feeding specifically labelled 14 C precursors to the pigment mutant, inhibiting the ALA dehydratase with LA, accumulating, extracting and analyzing the ALA, two pathways leading towards ALA could be established: glycine and succinyl CoA can be condensed to ALA and the 5 carbon skeleton of glutamate can completely be incorporated into ALA via a second pathway. The glycine‐succinyl CoA pathway dominates over the glutamate pathway, but both lead to chlorophyll formation.