SITE OF BIOSYNTHESIS OF a-TOCOPHEROL IN SPINACH CHLOROPLASTS

Tocopherol and plastoquinone synthesis in spinach chloroplasts subfractions.

Subfractions isolated from intact purified spinach chloroplasts are able to prenylate the aromatic moiety of cY-tocopherol and plastoquinone-9 precursors. The biosynthesis of a-tocopherol and plastoquinone-9 is a compartmentalized process. The chloroplast envelope membranes are the only site of the enzymatic prenylation in a-tocopherol synthesis whereas the thylakoid membrane is also involved i...

Localization and synthesis of prenylquinones in isolated outer and inner envelope membranes from spinach chloroplasts.

The prenylquinone content and biosynthetic capabilities of membrane fractions enriched in outer and inner envelope membranes from spinach chloroplasts were analyzed. Both envelope membranes contain prenylquinones, and in almost similar amounts (on a protein basis). However, the outer envelope membrane contains more alpha-tocopherol than the inner one although this prenylquinone is the major one...

Comparison of geranylgeranyl and phytyl substituted methylquinols in the tocopherol synthesis of spinach chloroplasts.

2-methyl-6phytylquinol and 2,3-dimethyl- Phytylquinol as Precursors of Tqcopherol Synthesis in Spinach Chloroplasts

The incorporation of [Me-‘“C] from SAM-[Me-r4C] into precursors indicates the following sequence of tocopherol synthesis in spinach: 2-methyl-6phytyIquinol (6-phytyltoluquinol) (la) ---, 2,3-dimethylphytylquinol (ph~ylpl~t~uinol) @n)--, y-tocopberol ($@+a-tocopherol (6). la is particularly preferred to 2methyl-5-phytyiquinol (lb) and Z-methyl-3-phytylquinol (1~). 1~ only forms 2a. 2~ is convert...

Site of prenylation reaction in synthesis of phylloquinone (vitamin K1) by spinach chloroplasts.

1,4-Dihydroxy-2-naphthoate [1, 21 as the crucial intermediate in the biosynthesis of menaquinones in bacteria is formed from shikimate [3] via chorismate [2] and o-succinylbenzoate [I]. Prenylation [4] and methylation [I] result in formation of menaquinones of different length of side chain. The principal steps of the synthesis of the naphthoquinone moiety are similar for both plants and bacter...