C

¿X^s CH20PP Isopentenyl pyrophosphate

4-Dlphosphocytldyl- ^r l\ -2-C-Methyl-D-erythrlol- I 1 „ „ -4-phosphate-2- 0 N NH2

-phosphate

Geranyl pyrophosphate

Geranyl pyrophosphate

-k*!i/CH20PP Dlmethylallyl pyrophosphate

CHvOPP Isopentenyl pyrophosphate ^ ^ CH,OPP

^ ^ J^ ^CHvOPP Farnesyl pyrophosphate

Isopentenyl pyrophosphate

Geranylgeranyl pyrophosphate

FIGURE 7.5 The initial stages of the carotenoid biosynthesis. Isopentenyl pyrophosphate biosynthesis by (A) mevalonate pathway or (B) l-deoxy-D-xylulose-5-phosphate pathway. (C) Isopentenyl pyrophosphate polymerization to geranylgeranylpyrophosphate. The involved enzymes are (1) mevalonate kinase; (2) mevalonate-5-pyrophosphate isomerase; (3) mevalonate-5-phyrophophate decarboxylase; (1') 1-deoxy-D-xylulose-5-phosphate synthase; (2') l-deoxy-D-xylulose-5-phosphate reductoisomerase; (3') 4-diphosphocytidyl-2C-methyl-D-erythritol synthase; (4') 4-diphosphocytidyl-2C-methyl-D-erythriol kinase; (5') 2C-methyl-D-erythriol-2,4-cyclodiphosphate synthase; (4) isopentenyl pyrophosphate isomerase; (5) farnesyl pyrophosphate synthase; (6) geranylgeranyl-pyrophosphate synthase.

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