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Cineole synthetase

Preliminary characterization of the partially purified cineole synthetase indicated that the enzyme, like other monoterpene synthetases, exhibited a pH optimum on the acid side of neutrality, was inhibited by thiol-directed reagents, and required a divalent cation for catalysis (Mn + was preferred) (Croteau and Karp, 1977a). A single protein appeared to be involved in conversion of the acyclic precursor to 1,8-cineole, and no free intermediates could be discerned in the reaction. A mechanism for the formation of 1,8-cineole was proposed that involved the hydration of a double bond of an enzyme-bound monocyclic intermediate, followed by displacement of the enzyme by the hydroxyl group to form the heterocyclic ring and simultaneously release the product (Croteau and Karp, 1977a). [Pg.377]

Romagni, J. G., Duke, S. O. and Dayan, F. E. 2000. Inhibition of plant asparagine synthetase by monoterpene cineoles. Plant Physiol. 123, 303-313... [Pg.136]

There are a number of allelochemicals among the mono-, sesqui-, and diterpenoids. In particular, plants in arid and semiarid regions produce diverse volatile terpenoids with allelopathic activity.5 Among the volatile monoterpenes, 1,8-cineole (4) and camphor (5) exhibit strong growth inhibitory effects on plants and are considered to be involved in plant competition. 1,4-Cineole (6), a minor isomer of 1,8-cineole, is a potent inhibitor of asparagine synthetase.6 -Menthane-3,8-diols (fir 7 and frw .r8), -menth-2-en-l-ols (cis 9 and trans 10), thymol (11), carvacrol (12), 1,8-cineole, cr-pinene (13), and /3-pinene (14) were isolated as allelopathic monoterpenes from Eucalyptus species.7 Eucalyptus trees also produce allelopathic sesquiterpenes including spathulenol (15), and a-, (3-, and 7-eudesmols (16-18).7... [Pg.540]

Figure 2. Effect of 1,4-cineole (circles), cis-2-hydroxy-1,4-cineole (triangles) and the commercial herbicide cinmethylin (squares) on the activity of asparagine synthetase from lupin. The dotted line represents 50% inhibition of enzyme activity. Figure 2. Effect of 1,4-cineole (circles), cis-2-hydroxy-1,4-cineole (triangles) and the commercial herbicide cinmethylin (squares) on the activity of asparagine synthetase from lupin. The dotted line represents 50% inhibition of enzyme activity.
The substrate specificity of 1,8-cineole, a-terpineol, limonene, and terpin-olene synthetases from sage has not yet been determined however, it is quite clear that the sage preparations, and similar preparations from Citrus (George-Nascimento and Cori, 1971 Chayet et al., 1977), can utilize both GPP and NPP for the biosynthesis of monocyclic monoterpenes. Only when such cell-free preparations are free of all competing enzyme activities can the true specificities of the monoterpene synthetases be accurately determined. [Pg.377]


See other pages where Cineole synthetase is mentioned: [Pg.118]    [Pg.214]    [Pg.218]    [Pg.218]    [Pg.219]    [Pg.2679]    [Pg.154]   
See also in sourсe #XX -- [ Pg.377 ]




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