Chloroplast biogenesis. Net synthesis of protochlorophyllide from magnesium-protoporphyrin monoester by developing chloroplasts.
Developing chloroplasts were isolated from greening Cucumis cotyledons in a cofactor-enriched medium and were incubated in the dark with 14C-labeled and unlabeled magnesium-protoporphyrin monoester. The metabolic pools between protoporphyrin and protochlorophyllide were monitored spectrofluorometrically. The incorporation of the 14C label into protochlorophyllide was also determined. It was shown that magnesium-protoporphyrin monoester, a postulated intermediate of the chlorphyll biosynthetic pathway, was convertible into protochlorophyllide with relatively high yields. Since protochlorophyllide is the immediate precursor of chlorophyll a it was concluded that magnesium-protoporphyrin monoester was indeed an intermediate of the chlorophyll biosynthetic pathway.
D002734:Chlorophyll / Q000031:analogs & derivatives*; D002736:Chloroplasts / Q000378:metabolism*; D008274:Magnesium / Q000378:metabolism; D008665:Metalloporphyrins / Q000378:metabolism; D011166:Porphyrins / Q000378:metabolism*; D011521:Protochlorophyllide / Q000096:biosynthesis*; D011524:Protoporphyrins / Q000378:metabolism*
D008665:Metalloporphyrins; D011166:Porphyrins; D011524:Protoporphyrins; D002734:Chlorophyll; D011521:Protochlorophyllide; D008274:Magnesium