Preparation of regio- and stereoisomeric di- and tetrahydrogeranylgeraniols and identification of esterifying groups in natural (bacterio)chlorophylls

Publication date: Available online 6 October 2017
Source:Bioorganic & Medicinal Chemistry
Author(s): Hitoshi Tamiaki, Kota Nomura, Tadashi Mizoguchi
All regioisomeric di- and tetrahydrogeranylgeraniols possessing the C2=C3 double bond were prepared as authentic samples. The synthetic C20-isoprenoid alcohols were separated well by gas chromatography. Based on the chromatographic analysis, the enzymatic reduction pathway of a geranylgeranyl group was investigated to identify the last stage of (bacterio)chlorophyll biosynthesis in phototrophs. The geranylgeranyl group was triply reduced to the phytyl group through the first regio- and stereospecific hydrogenation of C10=C11 to C10H–C11(S)H, the second of C6=C7 to C6H–C7(S)H, and the third of C14=C15 to C14H–C15H. The identification of the reduction sequence completes the biosynthetic pathways for naturally occurring chlorophyll-a and bacteriochlorophyll-a bearing a phytyl group as the esterifying moiety in the 17-propionate residues.

Graphical abstract

http://ift.tt/2ggrwby