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The Conversion of Phytoene-14C to Acyclic, Monocyclic, and Dicyclic Carotenes and the Conversion of Lycopene-15,15'-3H to Mono- and Dicyclic Carotenes by Soluble Enzyme Systems Obtained from Plastids of Tomato Fruits

1970; Elsevier BV; Volume: 245; Issue: 18 Linguagem: Inglês

10.1016/s0021-9258(18)62852-2

1083-351X

Santosh C. Kushwaha, Ginzaburo Suzue, C. Subbarayan, John W. Porter,

Lipid metabolism and biosynthesis

Abstract Proof is presented in this paper for the formation of acyclic and cyclic carotenes from phytoene-14C by soluble extracts of plastids obtained from fruit of different genetic selections of the tomato. The carotenes biosynthesized from phytoene-14C and the tomato selections used were the following: (a) cis- and trans-phytofluenes, neurosporene, neolycopene, lycopene, and ζ- and γ-carotenes, red tomato fruit plastids; (b) cis- and trans-phytofluenes, neurosporene, lycopene, and ζ-, δ-, γ-, α-, and β-carotenes, Hi-δ tomato fruit plastids; (c) cis- and trans-phytofluenes, neurosporene, lycopene, γ- and β-carotenes, Hi-β tomato fruit plastids, and (d) cis- and trans-phytofluenes, prolycopene, proneurosporene, lycopene, and β- and ζ-carotenes, Golden Jubilee variety tomato fruit plastids. Experimental evidence for the conversion of lycopene-15,15'-3H to mono- and dicyclic carotenes by a soluble enzyme system obtained from red tomato fruit plastids is also presented in this paper. Proof for the formation of the above carotenes from radioactive phytoene was obtained by cochromatography with authentic nonradioactive carotenes on an alumina chromatographic column. A close correspondence between radioactivity and absorbance for each carotene was observed. Further proof for the formation of acyclic and cyclic carotenes from radioactive phytoene was obtained by gas-liquid chromatography of the hydrogenated products. Coincidence between mass and radioactivity was also observed. The conversion of phytoene to phytofluene by the tomato enzyme systems appears to be dependent upon the presence of NADP, whereas the conversion of the latter compound to lycopene appears to require FAD and Mn++. The formation of lycopene is also increased in the presence of Mg++ and dithiothreitol.