Chlorophyll a - Biosynthesis

Biosynthesis

Chlorophyll a biosynthetic pathway utilizes a variety of enzymes. Genes code for the enzymes on the Mg-tetrapyrroles of both bacteriochlorophyll a and chlorophyll a. It begins with glutamic acid, which is transformed into a 5-aminolevulinic acid (ALA). Two molecules of ALA are then reduced to porphobilinogen (PBG), and four molecules of PBG are then coupled, forming protoporphyrin IX. When forming protoporphyrin, Mg-chelatase acts as a catalyst for the insertion of Mg into the chlorophyll a structure. The pathway then uses either a light-dependent process, driven by the enzyme protochlorophyllide oxidoreductase. Protochlorophyllide is a precursor to the production of a chlorophyll a molecule, or a light-independent process driven by other enzymes, to form a cyclic ring, and the reduction of another ring in the structure. Attachment of the phytol tail completes the process of chlorophyll biosynthesis.