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Vitamin E biosynthesis is initiated in the plant?s cytoplasm, but, except for the first step, biosynthesis takes place in the plastids. The necessary enzymes are localized at the inner membrane of chloroplast (Fritsche et al., 2017). Tocopherol (Vit. E) synthesis is initiated by homogentisate phytyltransferase (HPT) that condense homogentisate (HGA) and phytyl pyrophosphate (PPP). The condensation reaction between HGA and polyprenyl pyrophosphate produces 2-methyl-6-phytyl-1,4-benzoquinol (MPBQ), or can be direct precursors of ?- and ?-tocopherols, or can alternatively be methylated by a methyltransferase (MT/VTE3). The products of the later reaction are prenylated dimethyl-benzoquinols, namely 2,3-dimethyl-6-phytyl-1,4-benzoquinol (DMPBQ) which further cyclized by the tocopherol cyclase (TC/VTE1) to ?-tocopherol. The final step of Vit. E biosynthesis consists of the methylation of ?- and ?-tocopherols into ?- and ?-tocopherols (Mène-Saffrané 2017).
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